MUltlD.E.— CTENOMYS. 181 



Myodes ceconomus. 

 Mus oecouomus, Pallas, Glires, p. 225. pi. 17. fig. 19 (skull), 1778. 

 *a. Skull. Russia. From Mr. Brandt's Collection. 



The Lemming. Myodes lemmus. 



Mus lemmus, Pallas, Glires, p. 204. tab. 27. fig. xvii. 9 a, b. (skulls), 

 fig. xviii. 10 (fore-foot), 1778. 



a, b. Skulls. From the Zoological Society's Collection. 

 c. Skull. Sweden. 



The Tawny Lemming. Myodes helvolus. 

 *a, H. Skulls. Hudson's Bay. Presented by Dr. J. Rae. 



Back's Lemming. Myodes trimucronatus. 



*a. Skull. Hudson's Bay. Presented by the Hudson's Bay Com- 

 pany. 



Myodes torquatus. 

 *a. Skull. 



*b, *e. Skulls. Presented by Dr. J. Rae ; collected during his ex- 

 pedition in 1847. 



The Owinyak or Greenland Lemming. Lemmus grcenlandicus. 



Cervical vertebrae 7 



Dorsal 13 



Lumbar 6 



Sacral 3 



Caudal 10 



*a, *b, *c. Skulls. Presented by Dr. J. Rae. 



*d. Skull. Hudson's Bay. Presented by the Hudson's Bay Com- 

 pany. 



e,f. Skeletons. Wellington Channel. Presented by Captain Sir 

 Edward Belcher. 



CTENOMYS. 



Teeth :— Incisors £j ; Molars £j ; = 20. 



The Brazilian Ctenomys. Ctenomys brasiliensis. 



D' Orb. ,\oy. Amer. Merid. pi. 17. figs. 2-5 (skull). — Eydoux et Gervais, 

 Voy. de la Favorite, v. pi. 8. fig. 2 (skull).— Waterhouse, Nat. Hist. 

 Ma'mm. ii. p. 282. pi. 8. fig. 6 (skull). 



Cervical vertebrae 7 



Dorsal 12 



