8 THE NAUTILUS. 



more inflated than the Middlebury specimen. Ttie apparent fold on 

 the columella is evidently an individual malformation, as it does not 

 appear in any of the other specimens in the same lot. Compared 

 with typical cuhensis (Fig. 3), umhiUcata is more globose, with a 

 shorter and more obtuse spire. If the diflference holds good for the 

 northern form, umbilicata would be entitled to varietal rank. 



A single small specimen from Otter Lake (Lapeer ? County), 

 FiQ. 1. Michigan, (Text Fig. 1.) collected by the late Dr. Manly 

 Miles, seems referable to umbilicata. It is smaller than 

 the Rhode Island specimens (3.5x2) and differs some- 

 what in shape, the body whorl being somewhat shoul- 

 dered and the spire more acute and slightly more elevated. 

 But the characteristic axial (longitudinal) sculpture is 

 present although there is no trace of any spiral lines. The lip is 

 decidedly thickened within, and both it and the columella are pink. 

 The umbilicus is not as large as in the Rhode Island form. 



TjymncBa stagnalis v. perampla n. var. PI. II, figs. 5 and 6. 



This variety differs from the usual North American form, var. 

 appressa Say, by its shorter, rapidly acuminating spire and larger, 

 strongly shouldered body whorl ; the first three whorls of the spire 

 are slender and increase regularly in size ; the penultimate whorl is 

 disproportionately enlarged, swollen and subangulated by the flatten- 

 ing of the upper part of the whorl, which in the body whorl develops 

 into a prominent shoulder. 



Alt. (fig. 5) 45.5, diam. 26, length ap. 28, width 18 mm. 



Alt. (fig. 6) 45, diam. 23.75, length ap. 26, width 17 mm. 



Types (No. 1834 coll. Walker) from Houghton Lake, Roscom- 

 mon County, Michigan. Cotypes in the collections of the Philadel- 

 phia Academy and the Chicago Academy of Sciences. Also from 

 Douglas Lake near Petoskey, Michigan. All the specimens of 

 stagnalis from Houghton Lake that I have seen, more than 30, are 

 of this peculiar form, which apparently a well-marked local race. 



I have been informed by the late Dr. W. H. DeCamp that the late 

 A. O. Currier of Grand Rapids, who was the first to make known 

 the peculiar Lymnseids of Houghton Lake, intended to describe this 

 form under the very appropriate name which I have adopted for it. 



An elevated, almost scalariform example of this variety was 

 figured in the Nautilus, Vol. VI, pi. 1, fig. 6. It is interesting to 



