CROCODILIANS, LIZARDS, AND SNAKES. 567 



entire width, and not by the groove only. Presphenoid rndimental; 

 si)lienoi(l distinguished from basioccipital by suture; the latter with 

 descending compressed lateral processes. Petrosal with a short pre- 

 seinichciilar process, and a long subforamiual process; the latter ])re- 

 senting an open groove downward. Inferior face of frontal grooved, 

 jmstoptic not reaching frontal, triradiate, the two superior limbs shorter 

 than the inferior. Epipterygoid arising opposite ecto])terygoid and in 

 contact with a descending lateral process of the parietal and not touch- 

 ing petrosal. 



The hyoid apparatus is distinguished, like that of other Teiida% by the 

 great prolongation of the liypohyals anterior to the i)oint of atta(;liinent 

 of the ceratohyals. No second ceratobranchials or free ei)ibrancliials. 



In the mandible the Meckelian groove is closed except at the distal 

 portion. The coronoid is produced far anteriorly and not at all poste- 

 riorly on the external face, and the dentary does not extend niu<;b 

 beyond thetootb line. Surangular distinct; angle horizontal, expanded, 

 aiid forming an angle inwards. A distinct masseteric fossa, bounded 

 below by the angular. Splenial elongate, extending far anterior to the 

 splenial foiamen. 



Teeth with the crowns moderately compressed and unequally bicuspid ; 

 those of premaxillary and adjacent part of maxillary bone and corre- 

 sponding part of mandible, simple. 



Dorsal vertebrae with zygosphen. In both C. tessellatus and C. .sexlin- 

 eatus there are live cervical intercentra besides that of the atlas, and 

 the first rib is on the third or fourth vertebra. Two sacral dia{>oi)hyses, 

 both robust. Xeural spines distinct, moderate, highest in the caudal 

 series; ribs exte.nling to sacrum. Diapophyses very short except in 

 caudal region, where they extend for a considerable part of the length, 

 originating posterior to the middle of the centrum. On the distal part 

 of the caudal series there is an additional short spine like diapophysis 

 in front of the normal one, and the centrum is segmented between the 

 two. The segmentation disappears anteriorly with the disappearance 

 of thisprediapophysis. Chevrons intercentral. 



The suprascapula is of moderate dimensions and extends to the 

 summit of tiie neural spine. Scapula elongate, and with a large pro- 

 scapula. Coracoid with two deep notches. lnter(;lavicle with a very 

 long median limb, which is wide at the base and which covers an elon- 

 gate oval median fontanelle. Three sternal ribs, and two attached to 

 the xii)h()id rod. 



Ilium with a ])rominent anc/ulus crista'. Acetabulum entire; pubis 

 directed anteriorly at an acute angle, with median pectineal angle. 

 Ischia directed vertically downward, with angulus tuberosns, and pre- 

 and post ischiadic acuminate cartilages. 



It is remarkable that in the large species of the allied genus Tupi- 

 nambis the j)roscapular process is wanting. 



