VERTEBRATE REMAINS, PORT KENNEDY BONE DEPOSIT. 201 



HESPEROMYS Waterhouse. 

 A ramus with first and second molars and incisor, agreeing in detail of struc- 

 ture with the group with which our recent H. lencopus is type, and of the size of 

 that species, not certainly referable to the latter without further comparison. 



ANAPTOGONIA Cope. 

 Proc. Am. Phil. Soc, 1881, p. 91. 



Evotomys Coues, Proc. Acad. Nat. Sci. Phil., 1884, p. 186; Report U. S. Geol. Survey Terrs., N. Amer. 

 Rodentia, XI, p. 131, 1877 ; Hypud&us Keys and Bias, and Baird, not of Illiger. 



I have described from the Wheatley collection several species allied to or 

 belonging to the voles, and in this paper I add others. These forms are referable 

 to three genera, which are defined as follows : 



Pulp cavity and lateral grooves closed below ; teeth rooted ; Anaptogonia Cope. 

 Lateral grooves closed below, leaving pulp cavity open ; no roots ; Sycium Cope. 

 Lateral grooves and pulp cavities open below ; no roots ; Microtus Selys. 



The first term in this series of genera is the genus Phenacomys of Merriam, 

 where the crowns of the molars are short, and there are rather elongate roots. 

 This is naturally the primitive genus, and it is a curious circumstance that no fossil 

 species referable to it has been yet discovered. 1 



But one species of Evotomys has been obtained from the cave formations of 

 this country. 



Anaptogonia hiatidens Cope. 



Arvicola (A?iaptogonia) hiatidens Cope. Proc. Am. Phil. Soc, 1871, p. 91, fig. 18. 



Represented by two series of the inferior molars of the right side from the 

 second collection, and by a few others from the Wheatley series. The prism- 

 formulae of these teeth are as follows: (1) 1 six lobed f-1 ; (2) f 1 ; (3) 1 11. 

 The first molar is larger than both the others together. Its triangles f are isolated, 

 but anterior to these, one on each side, is well defined, but the dentine is con- 

 tinuous with that of the anterior lobe. This lobe consists of two prominent basal 

 loops, and two less prominent terminal rounded lobes, all unsymmetrical. There 

 are thus six keels on each side of the crown, and a rounded front border. The 

 triangles of the m^- are acute, and the anteriors of the opposite sides are not fully 

 separated from each other, a strip of dentine connecting them. In the m ¥ the 

 triangle of one side is less developed than the other, and one extremity of the last 

 column is smaller than the other, forming rather a curved process of a terminal 

 triangle of the opposite side. The pulp cavity is well enclosed below, and the two 

 roots are rather small and divergent. 



As compared with the A. rutila of the northern parts of the earth, this 

 species has doubled the linear dimensions of the teeth. 



1 See Merriam, North Atnerican Fauna, No. 2, 1889, p. 28 : On a new genus and four new species of 

 Arvicolinae. 



3 JOUEN. A. N. S. PHILA., VOL. XI. 



