PALJEONTOLOGICAL APPENDIX— EXTINCT KODENTIA. 947 



ARVICOLA (ISODELTA) SPEOTHEN Cope. 



Arvicola speofhen Cope, Proc. Airier. Phil. Soc. Phila. 1871, 87, fig. 13. 



Described from " tbe entire dentition of the left ramus mandibnli, with a few frag- 

 ments of tbe adjacent bone", from tbe Port Kennedy bone-cave, Pennsylvania. 

 Anterior lower molar witb one less triangle " than in any species of the section Arvi- 

 cola", and hence regarded as representing a new subgeneric type. 



ARVICOLA (PITYMYS) TETRADELTA Cope. 



Arvicola tetradclta Cope, Proc. Amer. Phil. Soc. Phila. 1871, 83, fig. 14. 



Described from a portion of the skull embracing the second and third upper molars. 

 Differs from the other known North American Arvicola; in the form of'the enamel loops 

 of the molars. Port Kennedy bone-caves, Pennsylvania. 



ARVICOLA (PITYMYS) DIDELTA Cope. 



Anicola didelta Cope, Proc. Airier. Phil. Soc. Phila. 1871, 89, fig. 15. 



Described from "the mandibular rami of five and the superior dentition of proba- 

 bly three individuals", from the Port Kennedy bone-caves. Allied to Arvicola (Pitymys) 

 pinetorum. 



ARVICOLA INVOLUTA Copo. 



Arvicola involuta Cope, Proc. Amer. Phil. Soc. Phila. 1871, 89, fig. 10. 



"Established on a nearly complete ramus maudibuli, with the dentition perfectly 

 preserved", from the Port Kennedy bone-caves. It is said to be " nearly allied to the 

 A. pinetorum, differing principally in the form of the anterior lower molar". About the 

 size of A. riparius. 



ARVICOLA SIGMODUS Cope. 



Arvicola sigmodm Cope, Proc. Amer. Phil. Soc. Phila. 1871, 90, fig. 17. 



Based on "three imperfect mandibular rami, two with the dentition complete, the 

 other with the posterior molar only wanting". About the size of A. riparius. Its 

 characters are said to be near those of " A. austera, Lee." 



ARVICOLA (ANAPTOGONIA) HIATIDENS Copo. 



Arvicola hiatidvns Cope, Proc. Amer. Phil. Soc. Phila. 1871, 91, fig. 18. 



Based on several molar teeth, which are several times larger than the correspond- 

 ing teeth of any of the above-named species, " and suggest the genus Fiber ". It is sug- 

 gested that it may not be referable to either Arvicola or Fiber, and that it may require 

 to stand as a separate genus. From the Port Kennedy bone-caves, Pennsylvania. 



GEOMYIDiE. 



GEOMYS BISULCATUS Marsh. 



Geomys bisulcalus Maksii, Amer. Joiiru. Sci. and Arts, 3d ser. ii, 1871, 121. 



Apparently nearly allied to Geomys bursarius. From Pliocene strata, near Camp 

 Thorne, Loup Fork, Northern Nebraska. 



