104 AMERICAN SPECIES OP VERTIGO. 



rounded ; with a slight impression over the palatal fold ; aper- 

 ture well rounded, truncate, the margins slightly everted, the 

 outer margin barely impressed at the auricle which is marked 

 by a slight angle projecting over the level of the peristome ; 

 no callus in the palate ; lamellae and folds three or four, small, 

 very short, of brownish color ; the parietal, columellar and in- 

 ferior palatal, and sometimes there is also a superior palatal. 

 Surface with very fine, irregular striae, somewhat shining,. 

 Alt. 1.5 to 1.6, diam. 1.1 mm.; aperture, alt. 0.6 mm." 

 (Sterki). 



Ehode Island : Warwick, J. F. Perry. Massachusetts: Dux- 

 bury, W. F. Clapp. 



Vertigo perryi STERKI, Nautilus xix, Sept., 1905, p. 53. 



"The present species resembles the low form of Vertigo 

 ventricosa Mse. in the shape and size of the shell, but the 

 formation of the aperture and its lamellse and folds is quite 

 different, the color is deeper and the surface less shining. 

 From the other three described, typically three-toothed, east- 

 ern Vertigos: tridentata Wolf, oscaricwia Sterki and parvula 

 Sterki, V. perryi is also very different ; in all of the three, the 

 parietal lamellae and palatal folds are much larger, longer, and 

 of whitish color ; the aperture is higher than wide ; the shells 

 are more elevated and of lighter color" (Sterki). 



The two localities now known for this strongly distinct 

 species are only about 45 miles apart, and both are close to 

 the sea. It is remarkable that a species so well characterized 

 could exist undetected for so long, close to centers of concho- 

 logical work. Specimens are contained in the collections of 

 Dr. Sterki, Mr. Perry, Mr. H. F. Carpenter, the Academy of 

 Natural Sciences, The Museum of Comparative Zoology and 

 perhaps some others. The example figured measures: length 

 1.6, diam. 1.05 mm. In some others the teeth are weaker, and 

 rarely there is the trace of an upper palatal fold. Often the 

 columellar lamella is hardly visible in a front view. The 

 lower palatal fold is often developed when the other teeth are 

 scarcely noticeable. The shell is very fragile. At Duxbury, 

 where it was collected by Mr. and Mrs. W. F. Clapp, it lives 

 on grass in a swamp, in wet weather as much as a foot above 1 

 the ground. 



