472 Annals of the Carnegie Museum. 



136. Pisidium glaciale Westerlund. 

 Pisidium glaciale Westerlund, I. c. 



The foregoing three species are cited from Dall, Alaska, MoUusca, 

 p. 144. 



137. Pisidium pulchellum (Jenyns). 



Cyclas pulchella Jenyns, Trans. Phil. Soc. Cambridge, 1832, p. 306, PI. XXI, fig. i. 

 Pisidium pulchellum B. B. Woodward, British Pisidia, 1913, p. 78, figs. 



Habitat. — Methy Lake, Athabaska (Richardson), Dall, /. c. Should 

 be verified. 



138. Pisidium mesae Theo. D. K. Cockerell. 



Pisidium mescB Theo. D. A. Cockerell, Journ. of Conchol., 6, p. 65 (named, not 

 described; the specimen is in the British Museum). 



Habitat. — Colorado. 



139. Pisidium harfordianum Prime. 



Apparently not described; but specimens under that name are in 

 collections. Roper, in The Nautilus, IX, p. 99, states that Dr. J. G. 

 Cooper says that ''harfordianum is most nearly resembling P. ran- 

 dolphii Roper." In the U. S. National Museum are a few specimens 

 of " P. harfordianum Prime," quite different. Eventually it might be 

 best to drop the name. 



140. Pisidium saginatum White. 



Pisidium saginatum White, Powell's Geology of the Uinta Mountains, 1876, p. 128. 

 Fossil. — Upper Cretaceous lignite, Evanston, Utah. 



Pisidium mighelsianum Clessin, Monogr. Cycladeen, in Martini- 

 Chemnitz, 1879, pp. 49, 57. 

 The author of the species in a letter received from him and dated 

 February 7, 1899, expressed the desire to have the species dropped. 

 What it had been, the writer could not ascertain. 



Grouping of the Species. 



Genus SpH/ERIUM. 



The genus has been divided into three subgenera: 

 Sph.eriastrum Bourguignat, of which the type and only species is 

 S. rivicola (Leach) of luiropc. Clessin has included S. sulcatum, 

 but it e\idenlly belongs to the following subgenus: 



