242 REPORT OF NATIONAL MUSEUM, 1898. 



esting peculiarities wliicli constitute difference from Crotaphytiis, to 

 which its general appearance suggests affinity. 



Premaxillary bone with elongate superior spine and posterior emar- 

 gination of inferior face. Nasals large, distinct, not shortened in front, 

 since the nostrils open forward. Frontal narrow, entire, grooved on 

 the middle line below, its posterior region pierced by the pineal foramen, 

 which is entirely anterior to the coronal suture (D. dorsalis). Suj)ra- 

 occipital loosely articulated anteriorly, and not distinct from exoccip- 

 itals. Prefrontals large, not extending over orbit; lachrymal smaller, 

 touched by jugal. Postfrontal small, distinct from the large postorbital. 

 The latter articulates extensively with both the jugal and supratem- 

 poral. Paroccipital small. Parietoquadrate arch well elevated. The 

 vomers together as broad as long, not produced posteriorly, with a 

 median fossa. Palatine flat, with a short maxillary process; pterygoid 

 flat in front, concave on the inner side behind for contact with the long 

 basipterygoid process. Ectopterygoid decurved at its inner extremity. 

 Quadrate with a narrow internal and a wide external conch. Postoptic 

 ah open sigmoid, reaching frontal above, with a median expansion with 

 rudiment of posterior limb. Petrosal very short above; subforaminal 

 portion prominent, with gi wide inferior groove looking downward. 

 Epipterygoid leaving pterygoid behind ectopterygoid process, and 

 reaching parietal without contact with petrosal. Presphenoid rudi- 

 mental; sphenoid and basioccipital united, and with prominent lateral 

 edges. Occipital condyle with exoccipital elements feebly distinguislied. 



In the mandible the Meckelian groove is completely curved. The 

 coronoid has little horizontal extent, and that is principally anteriorly 

 on the external side. The surangular and articular are fused together, 

 and the splenial is small. The dentary extends as far posteriorly as 

 the posterior border of the coronoid. The angle is prominent, flattened 

 so as to be horizontal, and has an internal angle. 



The scapula has a large j^roscapula directed upward, and the coracoid 

 has one emargination, which is large. The sternum has a narrow 

 median fontanelle which is not covered by the interclavicle. There are 

 four pairs of ribs articulated to the sternum, and two continue into the 

 approximated xiphoid rods. The ribs reach the sacrum. 



Vertebra? with a zygosphen articulation. Eight cervical vertebnii, 

 the anterior with a compressed hypapophysis, which soon becomes a 

 keel, which is absent on the eighth cervical and all following vertebne. 

 Four anterior vertebra? without ribs; seventh and eighth with long 

 ribs. Diai)ophyses very short, excejit in the caudal region, where they 

 are present for half its length, increasing in length to the base, where 

 they are quite elongate. Chevron bones intercentral. Neural spines 

 of dorsal region low; of caudal region rather elevated, oblique, and 

 preceded by a compressed vertical iirominence or anterior neural spine. 

 The centra are transversely segmented just in front of the diapophysis, 

 except in the anterior part ol the series. 



The angle of junction of the pubes is nearly right, and the i)ectineal 



