F. B. Loorais — Ehinocerotidcs of the Lower Miocene. 59 



Dicer other him aberrons sp. now 



Type Xo. 1,321 in the Amherst College Museum, a single 

 tooth, being either the first or second upper right-hand molar, 

 from the Lower Harrison beds near Agate Spring Quarry, Sioux 

 Co., Nebraska. While a single tooth is undesirable for a type, 

 this is so aberrant and specialized that the writer feels bound 

 to call attention to it. 



9 10 



Fig. 9. Diceratherium cooki P. ; a second upper niolar, one-half nat. size. 

 Fig. 10. Diceratherium dberrans ; type specimen, nat. size. 



The small tooth is considerably longer than wide, which is 

 unusual among the Diceratheres. Its cingulum appears as 

 remnants along the front and inner faces. The striking fea- 

 ture, however, is the development of the crista until it almost 

 equals in length the protoloph, having on its anterior side a 

 strong crochet-like process. In like manner the crochet is 

 developed to enormous size, and extends to the crista though 

 it does not unite with it. The great development of these two 

 usually moderate processes spreads the protoloph and metaloph 

 wide apart, causing the considerable lengthening of the tooth. 



Diceratherium minutum Cuvier = D. Croizeti Pomel. 

 See Osborn, Bull. Amer. Museum Nat. Hist., vol. xiii, p. 237, 1900. 



This form from France and Germany is one of the simpler 

 types of the genus, and occurs in the Upper Oligocene appar- 

 ently equivalent to the John Day. On both molars and pre- 

 molars the internal cingulum is greatly reduced, and the 

 crochet is but little developed, while on only unworn teeth 

 can any crista be detected. The region of the protoconule 

 is much swollen, making a fold which is very characteristic 

 of the European forms and has been termed an " antecrochet," 

 though the writer cannot feel that it is the true one. 



Diceratherium douvillei Osborn. 

 Bull. Amer. Museum Nat. Hist,, vol. xiii, p. 239, 1900. 



A second European species from the Lower Miocene (Burdi- 

 galian) of France. It is differentiated by Osborn by its size, 



