INSECTIVORA. 197 



which can be readily perceived from the measurements given. The poste- 

 rior crest of the molars appears to have less transverse extent than in the 

 larger species. This crest in the last inferior molar has a curved crenate 

 edge, with a small conic tubercle at its external extremitj-. The anterior 

 crest consists of two conic tubercles, whose apices converge, but whose 

 bases are closely appressed, and only distinguished by a superficial fissure. 

 The valley between the crests is iminterrupted. The preceding molar is 

 larger, and its posterior crest is like that of the lost molar. The apex of the 

 anterior crest is broken off. 



The ramus deepens rapidly forwards, and contains the enormous alve- 

 olus for the incisors. The coronoid process leaves the alveolar boi'der at the 

 line separating the last two molars, or, in the smaller specimen, a little an- 

 terior to this point, and is quite prominent. The masseteric fossa is well 

 marked, but shallows gradually anteriorly and inferiorly. 



Measurements, 



No. 1. 



u. 



Depth of ramus at penultimate molar 027 



Width of last molar anteriorly 008 



Length of crown of do 009 



No. 2. 



Depth of ramus of penultimate molar 029 



Dei)th of ramus at P-m. ii 043 



Length of five consecutive alveoli 047 



From the Puerco bed of N. W. New Mexico. Discovered by my as- 

 sistant, Mr. D. Baldwin. 



INSECTIVORA. 



To this suborder I refer the genus Esfhont/x, on account of the near 

 resemblance of such parts of the dentition as are known, to some of the 

 genera now existing. It is not unlikely that other genera of the Eocene 

 which have been referred to the Insectivora belong here. Esthonyx exhibits 

 an approximation to the Tillodonta in the restriction of the enamel-layers 

 of the incisors of one of the jaws to the anterior face only. The inferior 

 molars have much the constitution of those of Anchippodus, and in their 

 details resemble also those of Erinaceus. As compared with the Creodonta, 

 there is a near resemblance between these teeth and the tubercular molars 



