

SKELETON OF WILD RABBIT. II 



another point on which weight may be laid as connecting the Lagomorphi 

 with some at least of the true Ruminants, e.g. Capra and Cervus. 



As points of degradation in the Lagomorphi as compared with higher 

 mammals we may note in the Rabbit and Hare the absence or great 

 retardation of any anchylosis to each other of the basicranial bones, the 

 sutures between the basioccipital and basisphenoid and between the basi- 

 sphenoid and presphenoid remaining open not only when the occipital and 

 interparietal bones are fused, but even after these bones have become 

 abundantly fenestrated by senile absorption l ; the vertical and transverse 

 perforations in the basisphenoid communicating with the pituitary fossa ; 

 the small antero-posterior length of the palatal plates of the palatine and 

 maxillary bones leaving the stalked leaf-shaped end of the vomer exposed 

 behind them, and the anterior end of the same bone exposed in front of 

 them, when the dry skull is looked at along its base-line ; the development 

 of the ' foramina incisiva ' into wide fissures continuous with the latter of 

 the two sets of vacuities just spoken of ; the persistence of open fontanelles 

 in the occipital bone, in the interspace between that bone, the squamous, 

 and the tympano-periotic, in the space, that is, which corresponds to the 

 * asterion ' of Professor Broca, and in the interspace between the two last- 

 named bones below the backwardly-running bar of the squamous ; and 

 probably also the singular fenestration or vacuolation of the anterior and 

 upper part of the maxillaries. To these points, dependent upon a defi- 

 ciency of ossification, may be added the involution of the angle of the 

 lower jaw, which represents, though but rudimentarily, the inversion of that 

 part of the jaw in the Marsupials ; and the fusion of the optic foramina into 

 a single mesial foramen bounded inferiorly by the presphenoid much as in 

 Birds. 



Other points worthy of note in the Rabbit's skeleton, either as com- 

 pared with those of most Rodents of other suborders, or as compared with 

 those of other mammals, are presented to us in the imperfect differentiation 

 of the coronoid from the ascending ramus of the lower jaw; in the approach 

 to horizontality in the symphysis of that bone ; in the large size and back- 

 ward direction of the tympanic process of the tympano-periotic ; in the 

 small size of the infra-orbital canal and of the anterior part of the malar 

 process of the maxillary, and the large size of the free backwardly-project- 

 ing process of the malar bone proper; in the presence of large supra-orbital 

 processes attached in the middle and projecting freely at either end of their 

 length ; in the fixed attachment of the upper lamellae of the ethmoid to 



1 The persistence of patency in the sutures of the basis cranii appears to possess considerable 

 morphological value, but this cannot be said of the sutures of the roof of the skull. For example, 

 the interparietal anchyloses very early in the Subungulate Hystricomorphi, but it does the like also in 

 Sciurus, whilst it remains distinct for a long while in Myoxus, Castor, and the Murini, as well as in 

 the Lagomorphi. 



