0, ('. Mdis], \,ir Cretaceous Dinosaurs, 



423 



Hadrosaurus hr> viceps. 



Additional remains of the present species, Or (»ne nearly 



allied to it, have been secured since the description of the type 

 Bpecinu The latter has now been completely removed from 



the matrix, and on comparison with more perfect material 

 proves to be a portion of the right dentary bone. The remark- 

 able character of the teeth is well shown in the cuts below, 

 figures 1 and '2. 



There were at least live distinct series of teeth in place at 

 once, but only two or three rows were in use at the same time. 



2. 



Figure 1. — Portion of right dentary of Hadrosaurus breviceps, Marsh; side 

 view; one-fourth natural size. 



Figure 2. — The same; seen from above, a, anterior; ft, posterior. 



Claosaarus agilis, gen. nov. 



The small dinosaur described by the writer, in 1872, as 

 Hadrosaurus agilis^ proves on investigation to represent a 

 distinct genus, which may be called Claosaurus. The remains 

 of this reptile were found by the writer, in the Pteranodon 

 beds of the Cretaceous, near the Smoky Hill River in western 

 Kansas. After the species was described, the writer again 

 visited the locality, and secured other portions of the skeleton, 

 so that now the more important parts are available for 

 comparison. 



The teeth are of the Hadrosaurus type, but, apparently, 

 only a single row was in use at one time. The cervical verte- 

 brae are very short, and strongly opisthocoelian. The fore 

 limbs were very small. There are seven vertebne in the 

 Bacrum, firmly coossified. The caudals are longer than wide, 

 and the tail was quite elongate. 



* This Journal, vol. xxxvii, p. 335, April, 1889. 

 f Ibid., vol. iii, p. 301, April, 1872. 



Am. Joub. Sci— Third Series, Vol. XXXIX, No. 233.— May, 1890. 

 27a 



