1888.] ANATOMY OF THE MESOSUCHIA. 439 



this position, and formed a buckler covering the back from the neck 

 to the tail, as in Teleosaurus temporalis, with which E. E. Deslong- 

 champs identities the above-mentioned ' Gavial.' Whilst their 

 imbricated arrangement permitted some gliding of the scutes on one 

 another, and thus gave some degree of flexibility to the trunk, the 

 tongue-like processes must have imparted great security when the 

 limits of this mobility were a})proached. In their form and in the 

 position of their tongue these scutes differ from those of the Purbeck 

 Wealden Goniopholis. From those of the Wealden Bernissartia 

 they differ in having one and not a double keel, and in having a 

 tongue, which the scutes of Bernissartia want. 



The skeletons of these Peterborough Mesosuchians, so far as their 

 plan is illustrated by their remains in the Leeds Collection, differ 

 from those of the Eusuchia (1) in the amphicoelous character of all 

 their vertebrae except the two foremost and the two sacral ; 

 (2) in the absence of the largely developed carina wliich so 

 strongly characterizes the cervical vertebrae in Eusuchia ; (3) 

 their atlas differs in possessing a diapophysis placed on its pleur- 

 apophysis ; (4) their epistropheus differs in having a well- 

 developed diapophysis in the level of its neuro-central suture, and a 

 parapophysis on its centrum. 



In Gavialis ganyeticus I find the capitular and the tubercular 

 costal articulations both placed wholly on the pars odontoidea and 

 the second cervical riblet to articulate exclusively with this. In 

 tr. gan(/eticus, Crocodilus Jiiloticus, and in Alligator mississippiensis 

 I do not find any trace of a diapophysis on the atlantal neurapophysis. 

 In C. niloticus the capitulum of the second rib rests wholly on the 

 pars odont. ; and the tuberculum costse is borne chiefly on this, but 

 to a very small extent also on the centrum of the epistropheus. In 

 another example of this Crocodile the capit. and the tuberc. costae 

 are both wholly borne on the pars odont. In C. americanus the 

 second rib articulates wholly with the pars odont. In Alligator 

 lucius I find the capit. costte resting on the pars odont., and the 

 tuberc. costce articulating with a rudimentary diapophysis situated 

 on the neural arch of the epistropheus just above the neuro-central 

 suture. The plan of the articulation of the second rib is plainly 

 subject to variation in individuals of the same genus and even 

 species. Dr. G. Baur, in an example of Gavialis gangeticus examined 

 by him, found the capitulum only of the second rib articulating with 

 thenar* odont. ; and a minute diapophysis on the neural arch of the 

 epistropheus, with which the tubercle of the rib was probably con- 

 nected by ligament. Dr. Baur also found in Alligator mississip- 

 piensis the capit. costce articulating chiefly with the pars odont. and 

 by a minute facet witli the true centrum of the epistropheus. In 

 Croc, americanus, Scbneid., Baur also found the capit. costce arti- 

 culating with the pars odont. ; and the tuberc. costce touching the 

 neurapophysis of the epistropheus, but without articular facet on 

 this latter (43). These discrepancies and those observed by Koken 

 (44) make it very desirable that these details should be examined in 

 larger numbers of individuals of the same apecies. So far as the 



