Hatcher: CIf.nera and Spkciks ok Tuai hokon i mi,. 883 



In 1890"* Marsh described a third species Trac/iot/on /ongicc^s, 

 already referred to, from the Laramie of Converse County, Wyoming. 

 In the same communication he removed a fourth species which had 

 been described by him in April, 1872," as Hadrosaurus agilis from 

 that genus, creating for it a new genus Claosaunis. The type of 

 C/aosaiinis agi/is according to Marsh came from the Pteranodon hori- 

 zon of the Niobrara formation, near the vSmoky Hill River in western 

 Kansas, and consisted of a considerable portion of the skeleton. From 

 Marsh's description of the parts found and considering the geological 

 horizon in which the remains were discovered there would seem to be 

 little doubt that Claosaunis agilis is generically and specifically dis- 

 tinct from any of the preceding genera and should therefore be re- 

 tained. 



In May, 1892, Professor Marsh'"'' describes a fifth species of these 

 dinosaurs — Claosaurus annectens, founded upon a nearly complete 

 skeleton from the Laramie of Converse Co. , Wyoming. It is some- 

 what remarkable that Professor Marsh should have referred this speci- 

 men to this genus considering that the type of Claosatirus came from 

 the Pteranodon beds of the Colorado series. It would seem improb- 

 able that so highly specialized a genus should have continued unin- 

 terruptedly throughout so long a period as that which extended 

 from the Niobrara to the upper Laramie. Whether or not Claosaurus 

 agilis and C. aunectcns are generically distinct can alone be determined 

 by a careful comparison of the type specimens. Of the generic 

 identity of Trachodoti viirabilis of Leidy and Cope and Claosaurus 

 annectens there can be no doubt and there is little question but that 

 they are specifically identical. The almost complete skeletons which 

 were described by Cope and Marsh respectively as Diclonius niirabilis 

 and Claosaurus annectens were found in the same geological horizon 

 and in essentially the same locality, the former northeast of the 

 Black Hills and the latter southwest of the same mountains. Such 

 minor differences as do e.xist in the two skeletons are due either to dis- 

 tortion as a result of pressure, to individual variation, or at most the 

 little structural differences that are discernible are certainly of not 

 more than specific importance. We have already shown that Diclonius 

 is a synonym of Traciunlon, and Claosaurus annectens should there- 



"^ See Am. Jour. Sci., Vol. XXXIX., i8c,o, pp. 422-424. 

 '"See Am. Jour. Sci., Vol. III., p. 301, April, 1872. 

 2»See Am. Jour. Sci., Vol. XLIII., May, 1892, p. 453. 



