A MONOCJiiAl'll OF THE J5ATS OF NOltTll AMERICA. 



:i9 



brought nearly to the median line posteriorly, where tliey lie almost 

 in contact.* 



Mdxilhtri/ teeth. — Central incisoi- much larger than the lateral, con^ 

 tiguous witli its felloAV with sharp transverse cutting edge. The lat- 

 eral incisor very small, crown directed obliquely forward and inward 

 with an obscurely bilobed cutting edge. Canine rather small not 

 twice the length of the central incisor; the first premolar as broad as 

 the second but less abruptly pointed and touching canine. The second 

 l)remolar with wide ba.se where it rests against the first molar. An in- 

 terval exists between the two teeth. The first molar slightly inclined 

 backward with low protocone and obscure commissures, the i»osterior 

 being in great part absent. Paracone forming a smaller V than the 

 metacone but is more fluted than it. Hypocone obscure, low. The 

 second molar more (piadrate than the first ; the ]U'otocone somewhat 

 better defined. The Ys of the buccal cusps equal but the protocone 

 is tumid at an angle formed by it with the anterior border of the 

 crown. The third molar with i»rotocone having well defined commissnres. 

 The posterior limb of the paracone but half the length of the anterior 

 liuib. The remaining parts of the tooth not represented. 



MandihuJar teeth. — Incisors simple, even, obscurely bilobed. First 

 ]>remolar higher and broader (in profile) than the second and third. 

 This distinction is not so apparent when the parts are viewed from 

 above. The second and third premolars are progressively more pointed 

 and lower than is the foregoing. 



The first molar with the V much smaller than the triangular heel 

 whose anterior limb juts against the i»osterior limb of the V near its 

 base (perhaps, on the Avhole, to a less degree than is represented in 

 the figure). The base (/. e.., the lingual aspect) of the V is open, but 

 that of the heel is closed by a depressed commissure. The second molar 

 nuich the same as the foregoing, the Y and heel being subequal. The 

 third molar with the largest Y in the series but with a snuill, com- 

 pressed, deflected tubercle like heel. 



^ Paraconid in first lower molar smallest of any in the series. The 

 conjoined bases of the paraconid and metaconid deeply incised so as to 

 show the protocouid when the tooth is seen in profile on lingual aspect. 

 This character is not seen outside of this group, but reaches a higher 

 degree of development in Ischnoglossa. 



Locality. 



List of specivieuH. 



Sex. 



Fort Tunia, Cal .1 



Cape St. Lucas 



...do I 



--■do J J.lrf-. 



Near Tucson | cfimni, 



No locality J 



Presented by- 



Xaturo of speci- 

 men. 



Maj. G. 11. Thomas... Alcohol (type). 



John Xantus .\lcohol 



do do 



...do 



do 



do 



Collection. 



V.S.Xat.Mus 

 D... 

 Do. 

 Do. 

 n.i. 

 Oo. 



For other commonts nn the skeleton <•>( Mncnitiix. sec Introduction. 



