1869.] 263 [Cope. 



sus and 31. Mitchillii, wliile it is rudimental in M. maximus; in the lat- 

 ter the outer ridge bounding the meatus is jirolonged into a process 

 below, which is merely rudinicutary in the two species named. The 

 centra of the dorsal vertebraa are very cylindric, and shortened an- 

 tero-posteriorly. 



The full description of this species is reserved for the monograph 

 now in publication. The remains preserved are larger in their pro- 

 portions than those of the Ma3stricht animal. A portion of an indi- 

 vidual from the lower Green-sand bed of Monmouth Co., N. J., has 

 been submitted to me by the director of the geological survey of the 

 State, Prof. Geo. H. Cook. Portions of an individual of similar 

 proportions, which were found in Gloucester Co., are preserved in 

 the Cabinet of the Burlington Co. Lyceum. Vertebra3 quite similar 

 have been brought l^y Dr. F, V. Hayden from Nebraska. 



The M. Mitchillil may attain the dimensions of this species, though 

 none such have come under my observation. The names which may 

 be apiilled to this animal are few. The Atlantochehjs Mortoid Agass., 

 may refer to any large species of the genus, so far as our knowledge 

 goes; it has, however, never been described, and cannot therefore 

 retain this name. The Mosasaurus DeKayi Brown, is founded on a 

 tooth like that of M. MUchiUu, and cannot be distinguished on such 

 basis alone. The M. impar is only known from jaws and teeth, and 

 hence is the only species the name of which is liable to have been 

 duplicated here. It may belong to any of the American species here 

 enumerated, except M. MUchillii and M. missuriensis, whose teeth are 

 well known. As it is earlier named than, and may be the same as 

 M. depressus Cope, I do not describe the remains of the latter here. 



The ElUptonodon compressus Emmons, I do not consider to 'be a 

 Mosasauroid. The Baseodon reversus Leidy, is founded on pterygoid 

 teeth of some species. They resemble those of AL MitchiUii. 



Mosasaurus missuriensis Harlan. IcJilJii/osaums do. Harlan, 

 Trans. Amer. Philos. Soc, IV, 405, Tab. xx, 1834. Batrachiosaurus 

 Harlan. Ba'rachio!lierium Harlan. Mosasaurus neov id ii Meyer. M. 

 MaxhnUiam Goldfuss. M. missuriensis Leidy. 



An unusually perfect specimen of this species was recently ex- 

 humed by W. E. Webb, near the town of Topeka in Kansas. My 

 friend, Prof. J. Parker of Lincoln College of that place, informs me 

 that it is seventy-five feet in length, and the gentleman who discov- 

 ered it, that it measures eighty feet. Its mandibular rami are stated 

 by the latter to measure five feet. Measurements of the ver- 



