208 University of Kansas Geological Survey. 



Baptosaurus oiicliognatlius. 



Baptosaurus onchognathus Merriam, Ueber die Pyth. der Kans.-Kreide, 36, 

 1894. 



"Among the material collected by Mr. Sternberg there was, 

 in one of the boxes, some vertebrae and parts of a skull of like 

 appearance. They belong, apparently, to the same individual. 

 The single fragment of a jaw [pi. xxv, f. 6, after Merriam] 

 agrees, except the abnormal articular, with Plate carp us or Tylo- 

 saurus, distinct, however, in that the upper border of the articu- 

 lar, immediately behind the cotylus, instead of being directed 

 downwardly at an angle of about forty degrees, is turned ver- 

 tically upwards into a high process, from which the hind end of 

 the lower jaw has a hook-like appearance. Also at the posterior 

 inferior angle, where in Platecarpus and Tylosaurus there is an 

 elongated thickening, the border is thickened suddenly to more 

 than twice the thickness behind this place, and then becomes 

 suddenly thinner below the posterior end of the cotylus. There 

 is a much crushed quadrate present, which possesses a supra- 

 columellar [suprastapedialj process very much like that of 

 Platecarpus . } } In a note he says : " Since the completion of the 

 manuscript I have seen the original of Professor Marsh's Bap- 

 tosaurus, and am convinced that the remains in the Munich 

 museum really belong to the genus Baptosaurus." See, also, 

 pi. xli, f. 3. 



The lower jaw is so extraordinary that there will be no 

 trouble in referring a similar structure to the same genus, not- 

 withstanding the absence of other information concerning the 

 species. The type species appears to have been much distorted 

 from pressure, which may render the specific recognition some- 

 what difficult. 



The absence of all information concerning the genus, ex- 

 cept, practically, what is given above, prevents much if any- 

 thing being said about its proper position. The types of the 

 genus are from a much higher horizon than the Kansas species 

 ( which may be, however, from the Pierre) and it would be 

 remarkable if the genus should be found to really occur in 

 both places. It would seem strange that, in all the many hun- 



