58 



LAND AND FRESH- WATER SHELLS OF N. A. [PART L 



See remarks under 31. vancouverensis. 



In extreme forms of this species the revolving lines mark the 

 whole surface, even in the umbilicus and in the interstices between 

 the incremental striae. 



Fig. 98. 



Maci'ocyctis voyana, Newcomb. — Shell widely umbilicated, de- 

 pressed, planorboid, thin, translucent, with delicate oblique strife of growth, 

 and fine revolving lines, more developed below, very 

 light horn-color; spire scarcely elevated; whirls five, 

 flattened, rapidly increasing, the last broad, flattened 

 below, falling iu front; umbilicus very large; aperture 

 very oblique, removed from the axis, irregular truncat- 

 edly-ovate ; peristome thickened, subreflected, flexuose, 

 strongly depressed above and sinuate, ends approach- 

 ing, connected with a stout, elevated, brownish, ridge- 

 like callus. Greater diam. 21, lesser 18 ; height 4 mill. 



Helix (MacrocycUs) voyana, Newcomb, Am. Journ. 

 Conch. I, part 3, 235, pi. xxv, f. 4 (July, 186.')). 

 Macrocyclis voyana, Tryon, Am. Journ. Conch. II, 24(3, pi. iii, f. 9 (1866). 



Canyon Creek, Trinity Co., California. 



The specimen figured was received from Dr. Newcomb. 



LI9IAX, Linn. 



Body lessening towards the posterior extremity, which termi- 

 nates in a point. Back with a carina or keel when contracted, 

 convex when extended. Integuments with longitudinal elongated 

 glands, and anastomosing furrows arranged in the same manner 

 upon both sides. Mantle anterior, oval, marked with fine con- 

 centric striae or prominent wrinkles, unattached and free at the 

 front and sides, but connected with the body at its posterior part, 

 and containing in this part a testaceous rudiment or shell. 

 Locomotive disk not expanded at margin, having a narrow band 

 running longitudinally along its centre and separated from the 

 sides by a well-defined line or furrow. Respiratory orifice near 



