36 



Platecarpus Curtirostris, Cope ; Liodon cnrlirostris, Cope Pro- 

 ceed. Amer. Pliilos. Soc, 1871, December; Lestosaiiriis curtirostris, 

 Marsh, loc. cit. 



Mobrara chalk of the Smoky Hill Eiver, Kansas. 



aa. Relations of stapedial pit unknown : 



Platecarpus crassartus. Cope; Liodon crassartus^ Cope, Proceed. 

 Amer. Philos. Soc, 1871, 168 ; and December. 



Niobrara chalk of Eagle Tail, Colorado. 



Platecarpus simus. Marsh ; Lestosaurus simus, Marsh, loc. cit. 1872, 

 June. 



Niobrara chalk of the Smoky Hill Eiver. 



Platecarpus latifrons, Marsh : Lestosaurus latifrons, Marsh, loc. cit. 

 1872, June. 



Niobrara chalk of the Smoky Hill River, Kansas. 



Platecarpus gracilis, Marsh -, Lestosaurus gracilis. Marsh, loc. cit., 

 1872, June. 



Niobrara chalk of the Smoky Hill River, Kansas. 



Platecarpus (!) glandiferus. Cope; Liodon glandiferus, Cope, Pro- 

 ceed. Amer. Philos. Society, 1871, December. 



Niobrara beds of the Smoky Hill, Kansas. 



aaa. Stapedial pit excavated in a plane surface : 



Platecarpus mudgei. Cope ; Liodon mudgei, Cope, Proceed. Amer. 

 Philosophical Soc, 1870, p. 581 ; Holcodus mudgei, Cope, loc cit. 1871, 

 December; Bhinosaurus mudgei, Marsh, American Journ. Sci. Arts, 

 1872, June. 



Niobrara chalk of the Smoky Hill River. 



Platecarpus tectulus. Cope; Holcodus tectulus, Proceed. Amer. 

 Philos. Soc, 1871, December. 



Niobrara chalk of the Smoky Hill River. 



LIODON, Owen. 



Proceedings British Assoc. Advancement of Science, 1811, p. 144 ; Cope, 

 ■ Transac Amer. Philosophical Society, Extinct Batrachia, etc, 1870, 

 p. 200 ; Proceedings Amer. Philos. Society, 1871, December. 



The typical species of this genus, Liodon anceps, Owen, is very little 

 known, but few remains having so far been obtained from the English 

 chalk, its locality and horizon. Numerous North American species re- 

 semble it in the forms of the crowns of the teeth, and it is probable, 

 though not certain, that they agree in other respects also. Several 

 names have been proposed for our species; the earliest of which is Ma- 

 crosaurus, Owen. This name applies to species with compressed dorsal 

 vertebrae as L. Imvis and L. mitcMllii, both from the New Jersey green- 

 sand. For the species with depressed dorsal vertebra, as L. validus 



