CROCODILIANS, LIZARDS, AND SNAKES. 331 



row and is strongly grooved on the middle line below. The parietal is 

 short and wide, and is perforated by a large pineal foramen, which 

 touches the coronal suture. Parietoquadrate arch distinct. Supra- 

 occipital broadly but loosely attached, confluent with exoccipitals. 

 Prefrontals large, not reaching postfrontals above; lachrymal small 

 and joining jugal. Postfrontal a small splint; postorbital large, exten- 

 sively in contact with jugal and supratemporal. Paroccipital small. 

 Vomers short, divaricate, and separated by a deep notch behind. Pal- 

 atine with the vomerine process longer than the maxillary; palatine 

 foramen large. Palatines and pterygoids well separated from each 

 other on the middle line; ectopterygoid deflected at its internal extremity. 

 Basipterygoids developed. Quadrate with two conchs, the internal the 

 narrower. Presphenoid rudimental ; sphenoid and basioccipital coossi- 

 tied ; descending lateral processes of the latter strongly developed. The 

 supraforaminal part of the petrosal is very short; the infraforaminal 

 portion is produced beyond it and is nearly horizontal in position. The 

 foramen of eighth nerve is at the bottom of a fossa. Epipterygoid rest- 

 ing on ]>terygoid much posterior co ectopterygoid and reaching parietal 

 without touching petrosal. Occipital condyle not subdivided by 

 grooves. 



The hyoid system includes a pair of well-separated, short, second 

 ceratobranchials, and rather long and slender first ceratobranchials and 

 ceratohyals, which have no expansions. Hypobranchials moderate, 

 supporting ceratohyals at extremities. 



Mandible with Meckel's cartilage exposed at the distal part. Coro- 

 uoid not horizontally produced on external face. Articular and sur- 

 angular united. Splenial moderately elongate; dentary extending 

 behind coronoid on external face and deeply notched. Angle short, 

 hdrizontal, with short internal angle. Five cervicals with intercentra 

 in S. uudulatus and six in S. spinosus; three without ribs in both. Ribs 

 extending to sacrum. Sacral centra not coossifled. Sacral diapophyses 

 coossitied distally; the second with a posterior free angle distally. 

 Caudal diapophyses well developed at base of tail. From about the 

 eighth caudal the centra are segmented in front of the middle. 



Scapula with proscapular process ; coracoid with one notch. Sternum 

 with a very large fontanelle. Two ribs join the sternal plate; one 

 comes off the base of the xiphoid rod, and two articulate with the latter; 

 total, five pairs. The ilium has a small angulus crista^ and the aceta- 

 bulum is not emargiuate behind. The pubes are nearly transverse, and 

 tlie pectineal angle is external. The ischia are rather slender, and the 

 tuber is an angle. 



The middle and posterior teeth are feebly tridentate; the others are 

 simple. 



Viscera. — The liver is deeply emarginate posteriorly, and the left lobe 

 is larger than in many other genera of Iguanida". There is a distinct 

 colon. Tlie mesenteries are of the type most common in Sauria with 

 the exception that there are commonly two hepatoventral sheets. 



