312 PHILOSOPHICAL TRANSACTIONS. [aNNO 1787. 



All animals have, I believe, a smell peculiar to themselves : hov^r far this is 

 connected with the other distinctions, I do not know, our organs not being able 

 to distinguish with sufficient accuracy. The smell of animals of this tribe is the 

 same with that of the seal, but not so strong, a kind of sour smell, which the 

 seal has while alive ; the oil has the same smell with that of the salmon, herring, 

 sprat, &c. 



The observations respecting the weight of the flesh of animals that swim, which 

 I published in my observations on the economy of certain parts of animals, are 

 applicable to these also; for the flesh in this tribe is rather heavier than beef; 2 

 portions of muscle of the same shape, one from the psoas muscle of the whale, 

 the other of an ox, when weighed in air, were both exactly 502 grs. ; but weighed 

 in water, the portion of the whale was 4 grs. heavier than the other. It is pro- 

 bable therefore, that the necessary equilibrium between the water and the animal 

 is produced by the oil, in addition to which the principal action of the tail is such 

 as tends either to raise them, or keep them suspended in the water, according to 

 the degree of force with which it acts. From the tail being horizontal, the mo- 

 tion of the animal, when impelled by it, is up and down : 2 advantages are gained 

 by this, it gives the necessary opportunity of breathing, and elevates them in the 

 water ; for every motion of the tail tends to raise the animal : and that this may 

 be effected, the greatest motion of the tail is downwards, those muscles being 

 very large, making 2 ridges in the abdomen ; this motion of the tail raises the 

 anterior extremity, which always tends to keep the body suspended in the 

 water. 



Of the Bones. — The bones alone, in many animals, when properly united into 

 what is called the skeleton, give the general shape and character of the animal. 

 Thus a quadruped is distinguished from a bird, and even one quadruped from an- 

 other, it only requiring a skin to be thrown over the skeleton to make the species 

 known ; but this is not so decidedly the case with this order of animals, for the 

 skeleton in them does not give us the true shape. An immense head, a small 

 neck, few ribs, and in many a short sternum, and no pelvis, with a long spine, 

 terminating in a point, require more than a skin being laid over them to give the 

 regular and characteristic form of the animal. The bones of the anterior ex- 

 tremity give no idea of the shape of a fin, the form of which depends wholly on 

 its covering. The different parts of the skeleton are so enclosed, and the spaces 

 between the projecting parts are so filled up, as to be altogether concealed, giving 

 the animal externally a uniform and elegant form, resembling an insect enveloped 

 in its chrysalis coat. 



The bones of the head are in general so large, as to render the cavity which 

 contains the brain but a small part of the whole ; while, in the human species. 



