36 



FIRST CLASS OF THE VERTEBRATED ANIMALS. 



three compartments; the anterior portion, containing the two frontal 

 bones and the ^Ethmoid; the central portion, being the Parietal bones 

 and the Sphenoid; and the hinder portion, being the occipital Bone. 

 ' Among the occipital, the two parietal, and the sphenoid, are interposed 

 the Temporal bones, of which one portion properly belongs to the face. 



The bones found in tlie skulls of the Blaramalia frequently differ in number 

 from those of i\Ian. In some, the sutures which are always observable in the human 

 Cranium are obliterated at an early period of life, and two, three, or more bones, are 

 consolidated into one. In other species, some bones which become consolidated into 

 one in Man, remain during their entire lives as separate pieces. In the Elephant, 

 all the sutures of the skull soon become united into one solid piece. 



The occipital bone is divided into four portions, during the first or 

 Foetal period of life. The body of the sphenoid bone is then composed 

 of two middle parts, which are themselves subdivided, so as to form 

 three pairs of lateral wings. The temporal bone is composed of three 

 portions; one of these serves to complete the Cranium; another to 

 close the labyrinth of the Ear; while the third forms the walls or 

 parietes of the Ear-drum. These bony portions are multiplied to a still 

 greater extent in the first age of the Embryo; they coalesce more or less 

 rapidly according to the species; and the bones themselves finally unite 

 into one in the adult animal. 



The face in the Mammalia is essentially formed by the two maxillary 

 bones, between which passes the canal of the nostrils. In front of them 

 are placed the two intermaxillary bones, and behind the two palate bones ; 

 between them descends the single projecting plate of the asthmoid bone, 

 called the vower^ and upon the entrances to the nasal canal are situate 

 the bones distinguished by the proper term nasal. To the external parts 

 of its entrance are found the inferior turbinated bones; the superior 

 turbinated bones, on the contrary, belong to the sethmoid bone, and 

 are placed behind and above. 



To this complicated arrangement of the bones of the nose in the Mammalia, these 

 animals owe their superiority over man in receiving impressions of odoriferous effluvia. 

 The inferior and superior turbinated bones are greatly subdivided and convoluted. 

 The obvious design of this arrangement, is to extend the surface of the pituitary 

 membrane which is spread over them; and the extent of this surface is always found 

 to bear a constant relation to the acuteness of the sense of smell. 



The frontal sinuses, and in general the sinuses of all the bones in the neighbour- 

 hood of the nasal cavity, are very large, which has led several eminent physiologists to 

 consider them as subservient to the organ of smelling ; others consider these cavities 

 to be merely reservoirs for containing a watery fluid, which lubricates the parts 

 where this sense more especially resides. 



The Cetaceous tribes do not possess the sense of smell, nor have they any organ 

 ■which appears capable of exercising it. The two canals %vhich correspond to the nos- 

 trils are used by the "Whale tribes for transmitting air to and from the lungs. They 

 do not respire through the mouth, and the nostrils are placed on the top of the head. 

 By this arrangement they can swallow their food and keep the mouth in water, with- 

 out interrupting their respiration. 



The Jugal, or cheek-bone, unites the maxillary to the temporal bone, 

 and often to the frontal. The lachrymal bone occupies the internal 

 angle of the orbit, and sometimes a part of the cheek. In the embryo, 

 all these subdivisions are much more numerous. The tongue in the Mam- 

 malia is always fleshy, and attached to the hyoid bone {ps hyoides); it is 

 composed of several pieces, and suspended to the cranium by ligaments. 



It is generally supposed that the sense of taste resides exclusively in the tongue; 

 but this is not strictly correct. Some substances will excite particular tastes on pass- 

 ing over the inside of the lips and fauces. Blumenbach mentions that he had seen 

 a man, in other respects well formed, who was born without a tongue; yet he could 

 distinguish very readily the tastes of solutions of salt, sugar, and aloes, when rubbed 

 on his palate, and would express the taste of each in writing. The tongue of the 

 other Mammalia differs always from that of ]\Ian. In the Monkey tribes it is longer 

 and thinner. The entire Cat genus have horny integuments surrounding the conical 

 papillae, which are on the middle of the tongue. These are small hooks or claws, 

 sharp-pointed, and inflected backwards; so that when any of the larger animals of 

 this genus employ the tongue in licking the human hand, they tear off the skin. 



There does not appear to be any conical papills on the tongues of the Cetacea. 

 Cuvier was unable to discover them, even with a glass, upon the tongues of the Dol- 

 phin and Porpoise; and John Hunter compared the tongue of the large Whales to a 

 feather-bed. The worm (lytta) of the dog's tongue is a tendinous bundle of fibres, 

 running length-wise under the tongue. Casserius thought that it assisted dogs in 

 lapping up fluids. "We need scarcely observe that the practice of cutting out the worm 

 as a preventive of Hydrophobia, though sanctioned by Pliny, is an old prejudice 

 long since exploded. The Edentata, such as the Ant-eater and Rlanis, possess a long 

 worm-like tongue, which is apparently used for no other purpose than for taking up 

 the food. 



Their Lungs, two in number, are divided into lobes, composed of an 

 infinite number of small cells; they are always inclosed loosely in a ca- 

 vity formed by the ribs and the diaphragm, and lined by the pleura. 



The number of lobes in the lungs often varies in individuals of the same species, 

 tut in general they are more numerous than in the human species. A due proportion 



is always observed between the size of the lungs and that of the animal, although the 

 external form of the chest would lead an observer to arrive at an opposite conclusion. 

 The convexity of the diaphragm is not considerable, and the thorax is proportion- 

 ately wide in species having a short chest ; but, when the thorax is long, the dia- 

 phragm projects far into the chest, and the thorax is narrowed. Thus, in the rhino- 

 ceros, elephant, and horse, the diaphragm passes up into the thorax, and permits the 

 viscera to lie within the margin of the ribs. 



The Mammalia respire in a manner exactly resembling I\Ian. Atmospheric air 

 rushes into the cells of the lungs through the windpipe the instant after birth; it 

 is expelled and replaced by fresh air, and the action continues as long as life remains. 

 Although the muscles which enlarge the chest were to act with unUmited force, no 

 air could enter the lungs at each attempt at inspiration, if they were of a firm and 

 inelastic texture. A vacuum would, on the contrary, be formed between the pleura 

 pulmonalis or external covering of the lungs, and the pleura costalis or internal 

 lining of the ribs. But the lungs are highly elastic and free in their motion, so that 

 atmospheric air rushes into and dilates the cells, exactly in proportion to the expan- 

 sion of the area of the chest. When any cause prevents the air from rushing into 

 the lungs, death by suffocation or asphyxia is occasioned. On examination, the lungs 

 are found collapsed, as during expiration ; the right cavities of the heart, and the veins 

 'leading to them, are filled with dark blood, while the left cavities of the heart and 

 the arteries are nearly empty. In animals of the first class, which are hanged, deatli 

 is occasioned by strangulation, and not by apoplexy, as is frequently supposed. This 

 was proved by Gregory, who opened the windpipe of a dog, and passed a noose round 

 his neck above the wound. The animal, when hanged, continued to live, and to 

 breathe through the small aperture; but he died when the rope was attached below 

 the wound. M. Piichcrand asserts that a respectable surgeon in the Austrian army 

 had informed him that he once saved the life of a soldier by performing the operation 

 of opening the windpipe, a few hours before his execution. The soldier, feigning to 

 be dead, was cut down, delivered over to the surgeon for anatomization, and thus 

 finally escaped. 



The glottis through which the external air rushes into the lungs, is so small that 

 it may be readily obstructed when the epiglottis rises during the act of swallowing, 

 and the substance swallowed may stop up the mouth of the larynx. Anacreon, the 

 celebrated poet, was in this manner suffocated by a grape seed, and Gilbert, also a 

 poet, met his death in a similar manner. 



n The organ of voice, in the Mammalia, is always at the superior extre- 

 mity of the Trachsea or windpipe; — a fleshy prolongation, called the 

 velum palati or palate-curtain, establishes a direct communication between 

 the Larynx and the back part of the nostrils. 



" The human voice," says Sir Charles Bell, " commences in the Larynx, but rever- 

 berates downwards into the Trachea, and even into the chest, whilst it may be directed 

 with different effects into the cavities of the head, mouth, and throat. The organ of 

 voice is neither, strictly speaking, a stringed instrument, nor a drum, nor a pipe, nor 

 a horn, but it is all these together ; and we will not be surprised at this compHcation, 

 if we consider that the human voice is capable of every possible sound, — that it can 

 imitate the voice of every beast and bird, — that it is more perfect than any musical 

 instrument hitherto invented; — and, in addition to every variety of musical note, it is 

 capable of all combinations, in articulate language, to be heard in the different nations 

 of the earth. The essential and primary parts of the organ are the vocal cords, or 

 thyro-arytaenoid ligaments. The membrane lining the larynx is reflected over these 

 ligaments, so as to be drawn by them in their motions ; and this is what is meant when it 

 is said the organ is like a drum, for these membranes must vibrate in the air. The 

 muscles of the aryteenoid cartilages draw tight the vocal cords and their attached mem- 

 branes, and thus give them a certain tension ; and the air being expelled forcibly from 

 the chest at the same time, they cause a vibration of these hgaments and membranes. 

 This vibration is communicated to the stream of air, and sound is produced. This 

 sound may reverberate along all the passages from the lungs to the nostrils; but unless 

 there be a certain vibration in these cords of the larynx, there is no vocalization of 

 the breath. For example, a man in whispering articulates the sounds of the more 

 breath, without the breath being vocahzed and made audible by the vibrations in the 

 larynx. In singing, the vocalized breath is given out uninterruptedly through the 

 passages, the rising notes in the gamut being produced, first, by the narrowing of the 

 glottis, and secondly, by the rising of the larynx towards the base of the skull. In 

 the graver notes, the larynx is di-awn down, and the lips protruded; and in the 

 higher notes the larynx is elevated to the utmost and the lips retracted." The various 

 sounds emitted by different animals, to which we assign the terms roar, bray, howl, 

 purr, scream, whistle, bark, grunt, snort, and hiss, are all caused by peculiarities in 

 the construction of their vocal organs, which will be explained hereafter. 



As the Mammalia [generally] reside on the surface of the earth, where 

 they are exposed to moderate variations of temperature, their covering 

 of hair is but moderately thick; and in many of the animals inhabiting warm 

 countries this integument is generally deficient. The Cetacea, which 

 live entirely in the water, are, however, the only species wherein it is 

 altogether wanting. 



The abdominal cavity of the Mammalia is hung round with a mem- 

 brane called the Peritoneum, and their intestinal canal is suspended to a 

 fold of this peritoneum, called the Mesentery, containing numerous con- 

 globated glands, in which the lacteal vessels are ramified. Another pro- 

 duction of the peritoneum, called the Epiploon, hangs before and beneath 

 the Intestines. 



The uses of these several parts are precisely the same in the other Mammalia as in 

 Man ; but their form and extent depend upon the convolutions and length of the 

 intestinal canal; and therefore its reflexions, which form the omentum and the 



