The Hand Phrenologically Considered 4

The Hand Phrenologically Considered 4

In the first order, the birds of prey (_Raptores_), which includes the

eagle, the vulture, the owl, &c., for the purpose of striking their

quarry, and of securing it by a firm grasp, a strong muscular foot is

necessary, and we consequently find that the foot is provided with four

short muscular toes, three placed before, and one behind, all armed

with long, sharp, hooked talons, those of the thumb and innermost toe

being the longest, as the great duty of grasping is mainly performed

by them. The claws are also capable of being drawn back, they are

retractile like those of the cat; and the scales upon the upper surface

of the foot, as well as the skin covering it below, are strong and

tough for the purpose of protecting the member from the attacks of the

living prey upon which these creatures feed. The foot is also broadly

marked, the kind of marking and the size of the scales being especially

characteristic of the different genera and families. In the vultures,

which from their feeding on carrion do not require such strength of

foot, we find a notable deviation from this general character, the toes

becoming longer and slighter and the claws much weaker.

 

In the second order of birds, the perchers (_Passeres_ of Linnæus),

which comprehends sparrows, thrushes, larks, &c., the foot is

constructed for another and a very different purpose. Its chief office

is to support the bird in a horizontal position upon the boughs

and branches of trees and shrubs; hence the foot is long, the toes

slender, very flexible, and armed with long, straight, weak claws,

which are not at all retractile. All the birds of this order possess

four toes, one of which, the hind toe (_hallux_), is placed straight

out behind, the others being in front, and those situated externally

are connected to the middle ones at their bases. The scales covering

the foot are regularly disposed, and as they are not needed for the

purpose of defence, they are thin and tender, resembling ordinary scarf

skin. Even in the shrikes,—the birds of prey of this order, who feed

upon living creatures and use the foot for securing them, the claws

are not sharp, nor is the foot formed in such a manner as to ensure

a very secure grasp, and we accordingly find that they merely press

this organ upon their prey for the purpose of holding it. In a few

other families of this order, as the todies, the kingfishers, &c., the

foot is called upon to assist in feeding, and we consequently find

certain modifications of structure indicative of this office. In order

to strengthen the foot and to secure a firmer grasp, the external and

middle toes are united almost to the apex, and the strength of the hind

toe is considerably increased.

 

In the third order, the climbers (_Scansores_), or, as they have been

sometimes termed, the yoke-footed, to which the woodpecker and the

parrot tribe belong, the structure of the foot is modified for the

important purpose of enabling the creature to support itself in all

positions upon the stems and branches of trees. In order to effect

this the foot is made strong, short, and muscular, the claws sharp

and curved, and the toes are placed in a very different position to

that which they occupy in other orders, two of them being situated in

front and two behind. By such a disposition, a strong, secure grasp is

afforded; and thus it is that most birds belonging to this order are

enabled to climb in a vertical position, and to effect movements like

animals of the monkey tribe. In general these birds move very awkwardly

upon a level surface, but in one or two species the structure of the

foot is so modified that they can run upon the ground with great speed.

This is the case with the travellers’ friend of South America, and

with the ground parrot of New South Wales; and these creatures have

accordingly slender toes so constructed, that one of the two placed

behind can be brought in front at will, so that a larger and more

secure basis of support is thus afforded.

 

In the fourth order the scratchers (_Rasores_), to which the common

fowl, the pheasant, and the pigeon belong, the foot is adapted for

an instrument of active locomotion, as well as for the purpose of

procuring food by scratching in the earth. Hence we find it strong,

with a long muscular leg, and four toes, three before and one behind,

covered with broad scales and armed with short claws. The thumb, so

necessary for perching and climbing, is in birds of this order short,

rudimentary, and attached high up in the leg, so that the whole foot

being placed flat upon the ground, affords a very firm support to the

animal.

 

In the fifth order of birds, the runners (_Cursores_), to which the

ostrich, the emu, and the cassowary belong, the structure of the foot

is wholly that of a powerful instrument of locomotion. The leg is

long, the thigh strong and muscular, and the foot short and compact.

The toes which never exceed two or three in number, and of which

the second is the largest, are placed all in front, and armed with

very short claws, or, as in the African ostrich, with the outer toe

destitute of a claw. The scales are limited to the upper surface of the

foot, the under surface being flexible and occupied by an elastic pad

upon which the member rests. Such a conformation of limb, which would

be wholly useless for perching or climbing, is admirably fitted for

running—witness the swiftness of the ostrich—a creature equalling and

even surpassing the fleetest horse in speed.

 

In the sixth order, the waders (_Grallatores_), or stilt birds, as

the stork, the crane, the heron, &c., the leg is long and slender,

and the foot weak and covered with shield-shaped scales. The toes,

four in number, are long and straight, three being placed anteriorly,

and a shorter one (wanting in the plovers and lapwings) behind; they

are frequently palmated at their base, as in the stork; or, as in

the middle claw of the heron, toothed or notched like a saw; while

sometimes they have a narrow-winged appendage, running along the side,

as in the sandpipers. In search of their food, insects and small fish,

the individuals of this order frequent marshy places and shallow

waters, and many of them, as the stork and heron, are remarkable for

the unerring certainty with which they strike and seize their small

finny prey.

 

In the last order, the swimmers (_Natatores_), called also web-footed

birds, to which the goose, duck, and gull belong, the foot is modified

to assist in swimming. The legs are short; the four toes, all placed

in front, are united by a broad membranous expansion, and armed with

claws, the thumb being likewise brought in front, so that a greater

extent of surface may be given to this oar-like member. A foot

thus constructed would be wholly unsuited for perching, running, or

grasping, but it is well adapted to the wants and habits of these

aquatic birds.

 

_Mammals._—It is but in animals who suckle their young (_Mammalia_)

that the extremities attain their greatest state of developement, and

it is in the higher orders alone that they become useful as organs of

prehension, their office being limited in most of the lower tribes to

support and locomotion. In the lowest order of the series, or whale

tribe (_Cetacea_), the members, in the number of pieces of which they

are composed, bear a considerable resemblance to the fins of fishes,

though they are somewhat differently constructed, according as the

animal may be destined exclusively for an aquatic existence, like the

common sperm whale, or be more or less herbivorous, and consequently

terrestrial in its habits, like the dugong. In the former case, the

extremities are converted into broad paddles adapted for swimming, and

the feet are webbed; in the latter, the members are better developed,

the toes being free, and furnished with nails at their termination.

 

Of those orders of _Mammalia_ which are provided with four members—the

ordinary quadrupeds—some are furnished with a foot which appears to

be entirely without toes, their place being supplied by a mass of

horny tissue—the hoof. This is the case with the ruminants—animals

that chew the cud—as the cow, and with the horse; but in the latter,

as the name of the order implies (_Solidungula_), the hoof is solid,

while in the ruminants it is cleft; and hence by some naturalists these

latter animals have been termed _Bisulca_. Some slight differences

are perceptible in the construction of the feet of ruminants: thus

the chamois, the antelope, and other of the deer tribe, are furnished

with an additional toe, which, projecting backwards, affords a firmer

support to the body. In the thick-skinned animals (_Pachydermata_) the

toes can hardly be said to be free, being still partially enclosed in

the tough skin. It is from characters afforded by the foot that several

tribes of animals belonging to this order are mainly characterised:

thus the elephant has five toes to each foot, the rhinoceros three,

and the hog and hippopotamus four. Among those of the mammalia which

are characterised by the presence of four members with distinct and

separate toes and nails, but few are furnished with a true hand—that

is, a member with a thumb capable of being brought into apposition with

the other fingers. Carnivorous animals have either a foot with sharp

recurved and retractile claws, as the cat and tiger, or with straight

blunt claws, not retractile, as the bear; or the feet are small, almost

completely enveloped in the skin, and furnished with a membranous

expansion connecting the toes, as in the aquatic seal and walrus,

or river-horse: but in all these animals, although the fore-legs may

be more or less employed as instruments of prehension, they are not

used for the purpose of conveying food to the mouth. In some of the

gnawing animals, as the squirrel, the anterior extremity commences to

assume the function of a hand; and in a few of the kangaroo tribe,

such as the opossum, the hinder extremities are provided with a thumb

capable of being brought into apposition with the other toes. The hand

of bats, which serves these animals not merely for flying, but also

supplies the place of eyes and ears, enabling them to avoid objects

during the obscurity of night, is furnished with a sense of touch

extremely delicate. It is in man and the monkey tribe only that we

meet with a true and perfect hand. In the latter, both the fore and

hind extremities are constructed upon the same general principle as

the hand of man; and hence these animals have been styled four-handed

(_Quadrumana_).

 

“In man the upper members are disposed in a manner the most favourable

for the exercise of their functions as organs of prehension and of

touch: the fingers are long and flexible; they have all, with the

occasional exception of the ring-finger, separate movements, which

other animals (even those provided with hands) have not; the thumb,

which is apposable to these latter, is longer in proportion to the

fingers than in monkeys, and consequently can more readily apply itself

to the extremity of their palm or surface, and better seize small

objects. The nails, which are large and flat, cover the back part only

of the extremity of the fingers, so as to furnish a support to the

organs of touch without in the least depriving them of their delicacy.

The entire hand can execute rotatory movements the most extended; and

to the arm which supports it is afforded a solid attachment by means of

a large shoulder or blade-bone and a long collar-bone.” The statement

of Milne Edwards,[3] then, does not appear far removed from the truth,

“That the faculties of the _Mammalia_ are the more elevated in

proportion as their members are the better constructed for prehension

and for touch.”

 

 

USE OF A KNOWLEDGE OF THE FORM OF APPENDAGES TO TRUNKS IN GEOLOGY.

 

A knowledge of the form of the appendages to the trunk of animals is of

great service to the geologist, for it has been well and truly said,

that the organic remains imbedded in rocks are as medals struck in

commemoration of the great revolutions which the earth has undergone,

and so small a portion as the extremity of an animal is sufficient to

indicate its nature, and to enable us to ascertain the class and order

to which it belongs. Let us take a few examples. Some fossil bones

were discovered by General Washington near his seat in Virginia. Mr.

Jefferson, by whom they were examined, stated that they had belonged

to an enormous carnivorous animal, which from the size of its claws he

named the _Megalonyx_. Upon an examination more carefully conducted by

Cuvier, it was found that in the paw the second bone of the toe was

symmetrical, while in animal feeders furnished with retractile claws it

is curved, and not symmetrical; the first bone, too, was the shortest,

whereas in the lion and others of the feline tribe it is the longest.

Whence Cuvier was led to conclude that the creature in question was a

sloth of large dimensions, which fed only upon plants.