1881.] ^^* [Cope. 



any tubercle or ridge in tlie mouth of the posterior V-shaped valley. There 

 is a strong posterior cinguluoi, amounting to a narrow heel. As in the 

 case of the superior molar, the enamel where not worn is closely and 

 strongly wrinkled. The first superior premolar is characterized by the 

 very small development of its internal lobe, which is only a strong basal 

 cingulum. The crown proper has a sub-triangular outline, and the ex- 

 ternal face is flat and not concave. No external cingulum ; enamel 

 wrinkled. An external incisor has a large transversely extended crown, 

 without cingula. A low rib on the median line of the inner side. Enamel 

 wrinkled. In this and in another incisor, the base of the crown is con- 

 siderably expanded laterally. 



Measurements. M. 



^anteroposterior 035 



Diameters of crown M. Ill, sup. < transverse 041 



C vertical 020 



Width of M. Ill inferior, posteriorly 033 



^. •„ -r (anteroposterior 018 



Diameters P-m. I sup. \ . „. , 



^ ^transverse 014 



Diameter base crown I, II 034 



Length crown I, II 019 



Width base crown I, III 036 



EcTACODON CINCTU8, gen. et sp. nov. 



Char. gen. In Ectacodon the last superior molar has more of the ele- 

 ments of a posterior external "V than in Goryphodon, but not so much as 

 in Manteodon. The posterior transverse crest, it is true, has no oblique 

 posterior ridge joining it, to form with it more or less of a V. But the 

 external posterior angle of the crown supports a cusp, homologous with 

 the vertical rib found at the basal or external angles of the Vs in Palaosyops 

 and allied genera, and indicating the outlines of a V which lacks its pos- 

 terior side, in a manner not seen in Goryphodon. The penultimate and 

 ante-penultimate superior molars are like those of the latter genus. Skele- 

 ton unknown. I have a single species of this genus. 



Ghar. specif. Six superior molars of one skull represent this species. 

 They belong to a large animal, one about the size of the Manteodon sub- 

 quadratus. The last superior molar has a characteristic outline. It is not 

 oval as in the species of Goryphodon, nor quadrate as in Manteodon sp., 

 • but sub-parallelogrammic. The transverse diameter exceeds the antero- 

 posterior, and the anterior and posterior sides are parallel. The external 

 outline is slightly oblique and slightly notched in the middle. The internal 

 border is regularly rounded. The basal or second cingulum extends en- 

 tirely round the tooth from the posterior external cusp, round the inner 

 base to the anterior external base of the crown ; being absent only from 

 the external base. The first cingula both anterior and posterior are well 

 developed as in the species of Goryphodon, and unite in the prominent 

 internal angle. The posterior first cingulum joins the posterior basal cin- 



