THE NAUTILUS. 



137 



museum, collected by J. B. Tyrrell, in 1879, at McLeod Lake and 

 by Dr. G. M. Dawson, in 1889, at Nicola Lake, both in British 

 Columbia. 



" I have never seen any of the land or fresh water shells referred to 

 by Dr. Dawson in his Brit. N. Am. Bound. Report, and believe that 

 they went to the British Museum." 



Rev. George W. Taylor of Nanaimo, B. C, writes that a pair of 

 the shells collected by Lawson are the only ones in his collection and 

 that " the large Planorbis occurring on this (western) side of the 

 Rockies is P. ammon." 



In conclusion, therefore, it may be said that P. corpulentus Say, is 

 a valid species and entirely distinct from either the eastern P. trivol- 

 vis on the one hand, or the western P. ammon or binneyi on the other; 

 that it is a characteristic form of the Manitoba lake region, and ex- 

 tends from there into northern Minnesota and Michigan. Nothing 

 is known in regard to the animal. 



Bibliography. 



1824 Say— Long's Expedition II. 262, pi. XV. f. 9. 



1837 Beck — Index Molluscorum p. 118. 



1840 Whittemore— Am. Jour. Sci. and Arts 0. S. XXXVIII, 193. 



1848 Anthony — List of L. and F. W. Shells found in vicinity of Cincinnati. 



1844 Haldeman— lion. F. W. Univ. Moll. 19, pi. III. fig. 7-9. 



1842 Adams — Thompson's Hist, of Vt. 155. Reprint 5. 



1843 DeKay— Zoology of N. Y.— llollusca— 64. pi. VIII, 185* a. b. 



1845 Wheatley— Cat. Shells of U. S. 21. 

 1852 Jay— Cat. of Shells 267. 



1852 Gould— U. S. Ex. Ex. Moll. 114, f. 130, 130 a, 130 b. 



1856 Lewis— Proc. Acad. Xat. Sci. Phila. VIII, 260. 



1856 Carpenter— Rep. Moll. W. Coast of N. A. pp. 210 and 316. 



1858 Say— Binney's Ed. 128, pi. LXXIV, f. 9. 



1859 Cooper— Rep. Moll. P. R. R. Survey 378. 



1861 Tristram- -Cat. Coll. T. and F. Moll, in Guatemala, P. Z. S. 231. 



1864 Carpenter— Sup. Rep. Moll. W. Coast of N. A. pp. 532, 558, 599, 607, 



675. 



1865 Binney— L. and F. W. Shells II, 114, f. 190. 

 1870 Tryon— Hon. F. IV. Univ. Moll. pp. 199 and 202. 

 1872 Carpenter— Moll. West N. A. pp. 18, 44, 85, 93, 161. 

 1876 (?) Sowerby— Conch. Icon. XX. f. 4. 



1886 Clessin— Conch. Cab. Planorbis, 144. pi. 17, f. 4; pi. 22, f. 1. . 



1887 Grant— 16tb An. Rep. Geo. & Nat. Hist. Sur. Minn. 484. 



1893 Walker— Nautilus VI. 136. 



1894 Walker— Rev. Moll. Fauna of Mich. 18. 



