212 TEN years' progress IX VERTEBRATE PALEOXTOLOGY 



Hell Creek region of ^lontana and in Converse County, Wyoming, all, 

 however, referable to known species. So far as I am aware, knowledge 

 of but two skeletal elements has been gained since the publication of the 

 monograph — the sternal plates described by Brown and a hyoid element 

 approximatel}^ in situ in the t}^e specimen of Triceratops serratus at 

 Yale, the lower aspect of which has recently been freed from the matrix. 

 The new material of note has been largely collected by Brown and 

 Sternberg. The greatest need for further exploration seems to be in 

 the Judith Eiver and Edmonton beds, as our knowledge of thfe more 

 archaic Ceratopsia is still incomplete. 



Conclusion 



The desiderata include the completion of monographic studies upon 

 the Stegosauria, Theropoda, and Iguanodontia ; further evidence to 

 prove or combat Lull's contention that the Orthopoda were exclusively 

 confined to the northern hemisphere and why ; and f aunal and environ- 

 mental studies of the successive dinosaurian societies of the Cretaceous. 

 Of recent accessions a notable work is that of Sternberg, who has gone 

 into the apparently exhausted Converse County beds and found at least 

 seven Triceratops skulls and three remarkable Trachodons, two of whicli 

 still bear the integument. Barnum BrOwn, who has collected for the 

 American Museum in the Cretaceous beds of Montana and Alberta since 

 1902, has produced not only admirable results in the amount of material 

 gained, but in the discovery of some of the most remarkable dinosaurs 

 known to science. 



The German East African expedition and Baron ISTopcsa are further 

 important contributors to our knowledge of Cretaceous life. There is 

 still much to be done, and South America looms large in the gloom of 

 our ignorance as a most promising field for further exploration and 

 research. 



CHELONIA 

 BY OLIVER P. HAY^ 



The writer will endeavor to present here a brief account of the work 

 that has been done during the last ten years on fossil chelonians. The 

 time at his disposal being brief, he fears that a few papei-s. some im- 

 portant ones possibly, may be overlooked or not treated with entire 

 justice. 



* Introduced by R. S. Bassler. 



