1 882.] Geology and Paleontology. 831 



Char, specif. — The premolar is large as compared with the 

 molar, but the disproportion is not so great as in Ptilodus nuduc- 

 vus. It has one side convex and the other plane, and each is 

 bounded by a cingulum at the base. The sections of the denti- 

 cles are ovals, transverse to the edge of the crown. The grooves 

 which separate them are continued downward on the convex face, 

 but not on the plane face. The enamel is minutely wrinkled. 

 One end of the crown is lost, as it is also in the true molar. The 

 latter has the crown expanded laterally, so that the longitudinal 

 grooves are wide open, and not closed as in Catopsalis. The 

 median ones are transverse crescents in section ; those of one 

 edge are half crescents, and those of the opposite edge are the 

 least, and are transversely oval in section. In the fragment the 

 number of lobes is 4-3-4; the last row of small cusps being 

 complete, and turning into the median at both extremities. No 

 cingula. Elevation of crown of P-m. iv, .007 ; width of do. at 

 base, .006 ; width of molar, .006. 



This species was about the size of the Australian bandicoot, 

 and was probably a true marsupial. — E. D. Cope. 



A new form of T/ENIOdonta.— The Puerco beds of New 

 Mexico continue to produce new types of Mammalia. The 

 genus now to be described is probably a Taeniodont, and allied to 

 Calaiuodou, but the absence of the canine teeth renders the deter- 

 mination incomplete. The incisors, while of the form of those 

 of Calamodon, had a limited period of growth, and the root dis- 

 plays a contracted base. The enamel also extends but a short 

 distance on the anterior face of the tooth. The probable first in- 

 ferior incisors are quite small, but are generally like the second 

 or large ones. The superior molars have but a single conic root, 

 out in some of them a fissure of the external side marks the 

 usual place of division. The crowns are narrow and transverse 

 to the axis of the jaw. I call this genus Hemiganus, and the 

 species H. vultuosus. 



Char, specif. — Large incisors strongly curved, robust, wearing 

 with a strong posterior shoulder. Shaft with the dentine finely 

 and sharply ridged. Inferior apex compressed ; front regularly 

 rounded. Enamel ? ridged or smooth. Superior molar with nar- 

 rowed transverse crowns, and roots covered with a -thin layer of 

 cementum. There are one, perhaps two external cusps, but the 

 crowns are all much worn. One crown, perhaps inferior, is sub- 

 round with a notch, as in Cacamodon sp. Enamel short, with 

 e qual base, smooth. Length of first incisor, .026 ; diameter of 

 crown, anteroposterior, .008 ; transverse, .014. Length of second 

 incisor, .094 ; diameters of crown, anteroposterior, .029 ; trans- 

 verse, .019. Length superior molar, .0225; diameters crown, 

 anteroposterior, .010; transverse, .017. Diameter inferior molar 

 isecond specimen), anteroposterior, .011 ; transverse, .011. Dis- 



