2 THE NAUTILUS. 



wapiskat River, Keewatin. The type of S. Walkeri are from Lake 

 Michigan. 



Pisidium Idahoense Roper. 



Stewart River, near Mayo River ; one dead but perfect specimen 

 and an odd valve. Dr. Sterki writes that the " anterior part of the 

 hinge of the former is reversed." 



Pisidium compression Prime. 



Stewart River, near Mayo River ; one specimen. Mr. Mclnnes 

 has recently collected specimens of this species at Ozhiski Lake, 

 Attawapiskat River, at Kawinogans River (a branch of the Attawa- 

 piskat) and at the TYinisk River, Keewatin. 



Pisidium variabile Prime, var. 



Stewart River, near Mayo River; two specimens. Mr. Mclnnes 

 has recently collected three specimens on the Kawinogans River, 

 which Dr. Sterki has identified with this species. 



Pisidium scutellatum Sterki. 



Frances Lake ; fry only, one specimen. Dr. Sterki has recognized 

 a few specimens of P. scutellatum in collections made by Mr. Mclnnes 

 last year at Ozhiski Lake and the Kawinogans River, Keewatin. 



GASTEROPODA. 



Valvata mergella TVesterlund. 

 Stewart River, near Mayo River, two specimens. 



Yalvata Leivisii Currier. 



Valvata sincera of Haldeman, C. B. Adams, Dekay; TV. G. Bin- 

 ney, and many subsequent American writers, but, according to Dall, 

 not V- sincera of Say. 



Valvata striata of Lewis, but not of Pbilippi, 



Frances Lake, ten specimens, and Finlayson Lake, two specimens. 

 Presumably similar specimens were previously recorded by TV. G. 

 Binney, in 1865, under the name V. sincera, as having been collected 

 by Major Kennicott from the Peace River, Upper Mackenzie, and 

 Great Slave Lake. Frances and Finlayson Lakes both belong to 

 the Upper Mackenzie drainage system. 



