412 GEOLOGICAL SUEVEY OF THE TERRITORIES. 



greater vertical diameter than in the L. dyspelor, in the same portions 

 of the vertebral column. As a second character I note that (relying, 

 as before, on Gibbes's figures) the external angles of the depressed ball 

 are not so extended laterally in M. brumbyi. 



In size the vertebrae of the present animal exceed those of the 

 M. brumbyi. The latter has been hitherto the largest known species 

 of the order Pi/thonomorpha, exceeding two-fold in its measurements 

 the M. giganteus of Belgium. So the present saurian is twice as great 

 in dimensions as the New Jersey species I have called M. maxlmus. 

 If, as is not entirely certain, the M. missuriensis, discovered by Webb, meas- 

 ures 75 feet in length, the M. maximus measured 80, and the M. dyspelor 

 would not have been less than 100 feet in length. This would be the long- 

 est reptile known, and approaches very nearly the extreme of the mam- 

 malian growth, seen in the whales, though of course without their bulk. 

 Such monsters may well excite our surprise, as well as our curiosity, in 

 the inquiry as to their source of food supply, and what the character 

 of cotemporary animals preserved in strata of the same geologic horizon. 



The locality whence this reptile was procured is near Fort McBae, in 

 New Mexico. It was discovered by Dr. W. B. Lyon, at that post, 

 and by him sent to the Army Medical Museum at Washington, whose 

 director placed it in the collection of the Smithsonian Institution. 

 The attention to the paleontology of his neighborhood by Dr. Lyon 

 will always be cause of satisfaction to students, and his name will be 

 remembered with that of Turner, (discoverer of the Elasmosaurus pla- 

 tyurus, Cope,) Sternberg, and others. 



The stratum is the yellow chalk of the upper cretaceous, which has 

 yielded the L. icterieus, L. proriger, Polycotylus, &c, in Kansas, and 

 of whose western extension into New Mexico the present species is 

 evidence. 



CLIDASTES, (COPE.) 



(Proc. Acad.Nat.'Sci.,Pliila., 1868, 233; Proc. Bost. Soc. Nat. Hist., 1869,258; Transac. 

 American Philos. Soc, 1869, 211.) 



This genus is only known from the American cretaceous, though I 

 have little doubt that it will be discovered in other parts of the world. 

 It is distinguished from all other genera of the order by the presence of 

 the zygosphenal articulation of the vertebrae. The humerus is of the 

 most remarkable form, recalling slightly that of the mole among mam- 

 mals, and indicates a most powerful swimming paddle or flipper in the 

 position of the fore limb. The species do not average so large a size 

 as those of the two preceding genera ; the largest, G. 'cineriarum, did not 

 exceed 35 feet in length. There are four species known, of which two 

 occur in the cretaceous beds of Kansas. They are C. eineriarum, Cope, 

 Kansas ; G. iguanavus, Cope, New Jersey ; G. intermedins, Leidy, Kansas 

 and Alabama; and G.propython, Cope, Alabama. 



CLIDASTES INTERMEDIUS, (LEIDY.) 

 (Proceed. Acad. Nat. Sci., January, 1870, p. 4.) 



This species is established on several cervical and dorsal vertebrae, with 

 portions of mandibular rami and other bones, from Alabama, discovered 

 by Dr. Nott, of Mobile. 



They indicate a species intermediate in size between the two others here 

 described. The dorsal vertebrae are rather slender, more so than in G. 

 iguanavus, and with articular faces with cup and ball remarkably 



