CARNIVORA. 



473 



posterior aspect is generally small, directed 

 backwards, and separated by a strong occipital 

 crest from the anterior parts of the skull. From 

 this, in many instances, a strong, elevated, me- 

 dian crest passes forwards, which is remarkably 

 short in the lion, the white bear, the hyena, 

 the badger, and many others. It is remarkable 

 that in many of the Phocidae this crest does not 

 exist, whilst in other species it attains a con- 

 siderable size. The orbit and the immense 

 temporal fossa are confounded in one great 

 excavation ; the zygomatic arch is perfect and 

 of considerable size. The anterior opening of 

 the nares is large, and directed forwards, ex- 

 cepting in certain seals, in which it is placed 

 almost vertically, for the obvious purpose of 

 facilitating its exposure to the atmosphere when 

 these animals come to the surface to breathe. 



A remarkable peculiarity exists in this order, 

 in the existence of a bony process arising from 

 the internal surface of the occipital and parietal 

 bones, and separating the lobes of the cerebrum 

 from the cerebellum. This process, of mode- 

 rate size in the dogs, is much larger in the seals, 

 and still more developed in the cats. In the 

 dogs it is considerable from before backwards, 

 but small from side to side ; it is formed by 

 the parietal and the squamous portion of the 

 occipital. In the seals the parietal bone is not 

 concerned in its formation ; in the cats, on the 

 contrary, it entirely arises from this bone, not 

 being at all connected with the occipital. The 

 object of this bony tentorium is obviously to 

 support the different portions of the brain, and 

 prevent their pressing upon each other during 

 the sudden and violent movements of the ani- 

 mal, when springing upon its prey or leaping 

 with great violence. 



With regard to the substance of the bones of 

 the cranium in this order, although it may be 

 observed generally that they are of a medium 

 degree of thickness and solidity, there are re- 

 markable exceptions in some of the seals, in 

 which they exhibit an extreme degree of tenuity, 

 the object of which, in reference to the medium 

 in which the seals reside, and the necessity of 

 often rising to the surface to breathe, is suffici- 

 ently obvious. In the cats and other genera, 

 where extraordinary and sudden exertion is 

 frequently necessary, the bones altogether are 

 found to be remarkably compact and solid. 



A few details of the structure of the indivi- 

 dual bones composing the cranium will be 

 necessary, in order to shew how admirably 

 every portion is made to bear upon the general 

 objects of the whole organization. 



The frontal bones, (fig. 192, 193, 194, e,} 

 which, as in most other instances, are separate, 

 have a considerable developement of the zygo- 

 matic or external angular process, especially in 

 those whose habits are preeminently carnivorous, 

 as in the cats, the mustelidae, &c. In the ichneu- 

 mons it even extends so far as to meet the orbi- 

 tary process of the malar bone, and thus form 

 a complete orbitar circle ; the cats exhibit an 

 approach to such a formation, but in the other 

 tribes it is less and less marked, and in the seals 

 there is scarcely the vestige of this process to 

 be perceived. 



The parietal bones ( f) are of a quadrate form ; 

 they are early united in the mustelae, the cats, the 

 hyenas, and the bears ; in the dogs and in the 

 seals, &,c. they remain more durably separated. 

 The interparietal bone, as it is called, (a large 

 os triquetrum,) which is found in many ani- 

 mals, particularly during the young state, is 

 considerable in the dogs, in which it remains 

 permanently distinct from the parietal and oc- 

 cipital. Its form in these is that of an elon- 

 gated triangle, which extends forwards, sepa- 

 rating the two parietal bones for more than half 

 their length. In this instance it proceeds from 

 a single point of ossification, whilst in many 

 of the rodentia it arises from two centres of 

 developement. The crest which is formed 

 along the median line of the cranium, at the 

 junction of the parietal bones, and which forms 

 a continuation forwards from the ridge of the 

 occipital, is greatly developed in the older cats 

 and others. The lion and tiger, the wolf and 

 the bear, the badger and many others, exhibit 

 it in an extraordinary degree. Its object is 

 evidently to afford a strong and extended sur- 

 face of attachment to the powerful temporal 

 muscles, which are required to be enormously 

 developed for the purpose of cutting and tearing 

 in pieces the hard tendinous portions of the 

 animal's prey. 



The temporal bone (g) is divided, as in the 

 other mammalia, into a cranial or squamous, 

 and a petrous or acoustic bone. The former 

 constitutes the posterior and superior portion 

 of the zygomatic arch, and beneath the root of 

 this process is situated the articular cavity for 

 the reception of the condyle of the lower jaw. 

 Its transverse form, and the depth of its ante- 

 rior and posterior boundaries, afford a strong 

 and secure hold of the condyle, which, whilst 

 it thus moves freely within its limited sphere 

 of action, is restricted from any other than 

 a simple hinge-like motion. This circum- 

 stance adds greatly to the power of this parti- 

 cular kind of mastication. The squamous 

 portion is but small, and is externally more or 

 less convex. The acoustic portion is greatly 

 developed in the cats, and still more so in the 

 seals, a circumstance which will be further 

 alluded to hereafter. 



The occipital bone varies much in the car- 

 nivora. In the seals the superior or squamous 

 portion is large, obtusely triangular, and much 

 flattened, being in many species devoid of the 

 strong occipital ridge which is so prominent a 

 feature in all the other families of the order. 

 In the cats this process is very prominent and 

 strong, forming a solid attachment for those 

 powerful muscles which are necessary for the 

 forcible and even violent raising of the head in 

 tearing the prey to pieces. It is also strongly 

 marked in most of the Uriidte, particularly in 

 the white bear, the badger, the coati, &c. 

 The inferior portion, answering to the cuneiform 

 process, is in the seals remarkably broad and 

 thin, much more so than in any other of the 

 mammifera; and in this part there is in some 

 species of that family an oval hole of consi- 

 derable size, placed near the inferior margin of 

 the foramen magnum. This exists only in cer- 



