GEOLOGICAL SURVEY OF THE TERRITORIES. . 329 



Cliallc of Kansas. 



Olidastes 3 



Edestosaurus - ^ 4 



Holcodus ."- . 4 



Liodon - G 



17 



We have additional species from — 



North Carolina, (Mosasaiirus) 1 



Mississippi, (Platecarpus) 1 



Nebraska, (Mosasaurus) 1 



Making, with the others from — 



New Jersey 15 



Alabama 7 



Kansas 17 



A total of 42 



Of these I am not acquainted with any which extends its range into 

 any two of the areas above named, while some of these districts 

 possess peculiar genera. It is, nevertheless, premature to draw any 

 conclusions as to geographical range, as most of the species are 

 known from but few specimens as yet. 



The present investigations have added some points of importance to 

 the history of t])e structure of the order. 



First, as to the pterygoid bones. It appears that these elements are 

 thin i^lates, having a free laminar termination, and are entirely tooth- 

 less. They articulate with the palatines by a process which fits the pos- 

 terior emargination of the latter. In the Edestosaurus tor tor they are 

 about half the length of the palatines. They i^resent no indications of 

 ectopterygoid. The bones named by authors pterygoids, in imitation 

 of Ouvier, are elongate palatines, and the external i)rocess extending 

 to the maxillary is that seen in Varani, serpents, &c., and is at no time 

 distinct from the palatines. 



Secondly, as to the parieto-squamosal arch, which is well developed. 

 It is preserved in Roleodus ictericus and Liodon cnrtirostris in its parietal 

 part, and R. coryphwus in the squamosal part. It was quite strong in the 

 species named. 



Thirdly, as to the pelvis. This part, which has been observed by Marsh 

 in Edestosaurus dispar, is unusually perfect in Liodon dyspeJor. The 

 pubes are the only elements united below, forming a weak support to 

 the abdomen. The ilia are slender, not united with the vertebral pro- 

 cesses above, or without indications of such contact. The ischia are 

 the most slender and directed backward. The peculiarities of the pelvis 

 add to the broad distinction between this order and the Laccrtilia, 



Fourthly, in the hind limb. The femur of X. crassartus has been 

 described by the writer, and Professor Marsh asserts its existence in 

 Jjiodon, CUdastes^ and Edestosaurus. The present collection exhibits both 

 femur, tibia and fibuhi of L. dyspelor, and these elements are now first 

 described. The first mentioned is not larger, sometimes smaller, than 

 the humerus, and has a i)rominent tro(ihanter, nearly connected with 

 the head. The shaft is not curved, and the distal end is expanded. 



