MICROrHYSA. 169 



(hiring the summers of 1873, 1874, in the virinity of the 40th paralh-l. Lake 

 of tlie Wooils to the Kocky Mountains ; liritish North American lioundary 

 Commission; Report on tlie Geology, etc. Montreal: 1875. pp. 347-350. I 

 have seen young individuals kindly sent mo by Mr. Dawson, and suspect thera 

 to be immature individuals of some variety of P. strigosa. The original descrip- 

 tion here follows : — 



Shell conspicuously umbilicated, globosely deprcs.scd, solid, coarse ; whorls 

 oarinate at the periphery and subcarinate near the umbilicus, giving the mouth 

 a tlistinctly rhomboidal form in young specimens ; peripheral carination almost 

 obsolete on the last half whorl ; aperture roundedly lunate, very oblique, slightly 

 redexed at the umbilicus, so as to interfere somewhat with its circular outline ; 

 })cristome acute, thickened within ; callus delicate, transparent ; whorls 5^ ; 

 suture slightly impressed, becoming more distinct in the last half whorl ; sur- 

 face marked with coarse transverse wrinkles and faint revolving lines, the latter 

 scarc(dy perceptible on the outer whorl ; color, dull yellowish, with four brown- 

 ish revolving bands, two of which appear pretty constant, and are situated on 

 each side of the peripheral carina, which is generally whitish ; the two remain- 

 ing bands near the suture and umbilicus respectively, fainter and less constant. 

 Animal resembles H. solitaria in general form, pale, with brownish spots. 

 Greatest diameter 17 mill.; least diameter 14 mill.; height 11 mill. Young 

 specimens only 4 mill, in diameter are very strongly carinated, and flattened 

 above ; semi-transparent, brownish-tawny in color ; delicately marked with 

 close revolving and transverse lines. 



This shell is closely allied to Helix solitaria, but is smaller, darker-colored and 

 rougher, more distinctly carinated, especially in young specimens ; the shell is 

 also somewhat thicker, the umbilicus is narrower, and the lip encroaches slightly 

 on its circular outline. Loc. "Waterton Lake. Rocky Mountains. 



MICROPHYSA, Albers. 



Animal as in Patula. 



Shell umbilicated, depressed, thin, delicately striate, scarcely shining; spire 

 flattened ; suture distinct ; whorls 4-5, rather convex, gradually increasing, 

 the last not descending ; aperture roundly lunate ; peristome thin, perfectly 

 simple, its extremities converging. 



A West-Indian genus. Two of its species have been introduced into the 

 Southern Region. One indigenous species has, however, been found in the 

 Central Province and one in the Pacific Province. 



The jaw was supposed to be ribless, and hence the position of the genus in 

 the systems ; I retain it here, though 1 have found that it has numerous, flat, 

 broad, crowded ribs. Li M, turhiniformis (Ann. Lye. Nat. Hist, of N. Y., X. 

 79, PI. IL Fig. 2) the ribs seem to be of the character common in Bulimulus, 

 Cylindrella, etc. (See p. 44.) 



Lingual membrane of vortex, turhinifoi-mh, incrustata, Lanaingi, and Ingersolli 

 only known. The base of attachment of the centrals and laterals is peculiarly 

 quadrate ; both have decided side cusps and cutting points. The change into 



