KANSAS MOSASAURS. 



BY S. W. WILLIS TON AND E. C. CASE, 



PART I, CLIDASTES, WITH PLATES II-VI. 



The group of extinct Cretaceous reptiles known as the Mosasaurs 

 or Pyihonomorpha was defined by Cope, "to whom Science is so 

 largely indebted for its present knowledge of this interesting order of 

 reptiles" (Marsh), in 1869. * Although some of the characters 

 assigned by him to the order have since been shown to be inapplic- 

 able, and the group to have less value, yet his name, Pythonomorpha, 

 has been generally retained. Lydekker and Zittel have assigned to 

 the group a subordinal value, as has also Marsh, though under a dif- 

 ferent name. Owen rejected it entirely, and Baur, more recently, f 

 has united it with the Varanidae to form a super-family, as follows : 



Suborder Platynota. 



Super-family Varanoidea. 

 Families Mosasauridae, Varanidae. 



Super-family Helodermatoidea. 

 Family Helodermatidae. 



The group, whatever may be its rank or position, includes, so far, 

 the following genera : Mosasaiirus Conyb., Liodon Owen, Platccarpus 

 Cope, Clidastes Cope, Baptosaurus Marsh, Sironectes Cope, Plioplate- 

 carpus Dollo and Hainosaurus Dollo. Ptcrycollasaurus Dollo, found- 

 ed upon Mosasauriis niaxiviilianus Goldf. , is omitted as doubtful. All 

 of these genera, save Plioplatecarpus and Hainosaurus, have been 

 recorded from North America, Clidastes, Baptosaurus and Siro7iectes 

 being peculiar to this country. Of these latter three genera, however, 

 Clidastes alone is well known ; but this genus is suspected by Lydekker 

 of being the same as the imperfectly known European Geosaurus 

 Cuvier. Thus it seems that the genera, or at least the most of them, 

 have a wide distribution; Platecarpus, in fact, is said to occur in New 

 Zealand. 



In America, members of the group have been discovered in the 

 Cretaceous deposits of New Jersey, Alabama, North Carolina, the 



*Proc. Bost. Soc. Nat. Hist., p. 253. 

 f Science, xvi, p. 202, Nov. 7, 18'JO. 



(ij) KA.N, UNIV. m'AK., VOL. I, .NO. I,JLLV, lSy2, 



