OF THE ANIMAL FRAME. 



every class, order, and even genus of animals, except a very few of the 

 soft worms and insects in their first and unfinished state. 



It is hence the cerambyx, and several other tribes of insects, are able 

 to make that shrill sound which they give forth on being taken, and which 

 appears like a cry from the mouth, but is in reahty nothing more than the 

 friction of the chest of ihe insect against the upper part of its abdomen and 

 wing-shells. And it is hence, alyo, that the ptinus fatidicus^ or death- 

 watch, produces those measured strokes against the head or other part of 

 a bed in the middle of the night, which are so alarming to the fearful and 

 superstitious ; but which in truth are nothing more than a call or signal by 

 which the one sex is enticed to the other, and is merely produced by the 

 insect's striking the bony or horny front of its head against the bed-post, 

 or some other hard substance. 



Having, then, taken a brief survey of the elementary nature and chemi- 

 cal composition of these harder parts of the animal frame, I shall proceed 

 to make a few remarks upon the relative powers of each, and their diver- 

 sified applications amid the different kinds of animals in which they are 

 employed. 



The BONES in their colour are usually white ; but this does not hold uni- 

 versally, for those of the gar-pike (esox Belone) are green ; and in some 

 varieties of the common fowl they approach to a black ; Abelfazel remarks 

 this of the fowls of Bera, and Niebuhr of those of Persepohs. 



The bones of an animal, wherever they exist, are unquestionably the 

 levers of its organs of motion : and so far the mechanical theorists are cor- 

 rect. In man and quadrupeds, whose habits require solidity of strength 

 rather than inflexibility of accommodation, they are hard, firm, and unphant, 

 and consist of gluten fully saturated vvith phosphate and carbonate of lime. 

 In serpents and fishes, whose habits, on the contrary, demand flexibility of 

 motion, they are supple and cartilaginous ; the gluten is in excess, and the 

 phosphate of lime but small in proportion to it, and in some fishes alto- 

 gether deficient in the composition of their skeleton, though still traceable 

 in their scales and several other parts. In birds, whose natural habits de- 

 mand levity, the bones are skilfully hc Uowed out and communicate with 

 the lungs, and instead bf being filled with marrow are filled with air, so 

 that the purpose for which the structure of birds was designed is as ob- 

 vious, and as deeply marked, iri the bones as in the wings, whose quills 

 also are for the same reason left hollow, or rather are filled with air, and ir^ 

 many tribes communicate with the lungs as the bones do. 



The skeleton of the cuttle-fish (sepia officinalis) is extremely singular ; 

 » its back-bone, for some purpose unknown to us, is much broader than that 

 of any other aquatic animal of the same size, and of course would be much 

 heavier but for a curious contrivance to prevent this effect, which consists 

 in its being exquisitely porous and cellular, and capable, like the bones of 

 birds, of becoming filled with air, or "exhausted of it, at the option of |he 

 animal, in order to ascend or descend with the greater facility. It is an 

 animal of this kind, or closely akin to it,* that inhabits the shell of the 



* The animal has cora?nonly been supposed fo be a real sepia or cuttle-fish ; but several 

 naturalists have of lute doubteu this, inHsmuch as tbere are a few marks of distinction that 

 seem to take it out of this genus. Ratinesque has hence made another genus, for the purpose 

 of receiving those which possess these distinctive signs ; and Dr. Leach has lately distinguish- 

 ed it specifically, in consequence of specimens sent home from the unfortunate Congo expe- 

 dition, as collected by Cranch, by the name of Ocythoe Cranchii. Even this animal, how- 

 ever, is regarded as a parasite \xi the shell, and only possessing it when empty. The proper 

 f^^m^\ is not known to the present hour. See Phil. Trans. 1817, p. 293. 



