62 



RANDOM NOTES ON NATURAL HISTORY. 



The Shell-Bearing Mollusca of Rhode 

 Island. 



BY HORACE F. CARPENTER. 



Chapter XXXT. 

 Genus Vertigo, Muei.er, 1774. 



Shell minute, rimate, oval, frequently 

 sinistral ; apex obtuse ; whorls five or six ; 

 aperture, irregular, multi-dentate ; lip white, 

 expanded. 



There are about one hundred species of 

 Vertigo distributed between four sub-genera, 

 of which Alaea, Jeff., contains eighty-five. 

 This is the onl}' sub-genus represented in 

 America. The American s^:ecies are eight 

 in number and of these, six inhabit New 

 England. They resemble each other so 

 closely that it is onlj' by the teeth that they 

 can be distinguished apart until after a 

 long experience in working up these species. 

 The teeth are scarcely visible to the naked 

 eye, and require a microscope to determine 

 their character. 



Very little indeed, can be said about 

 these minute shells. Their habits and ap- 

 pearance are very similar, and a scientific 

 description of one will apply to all, except- 

 ing as regards the number of teeth, their 

 position, etc. 



109. Vertigo (Al^a) Bollesiana, Morse. 



This species was discovered in Maine and 

 described by Prof. E. S. Morse, ^nn. N. K 

 Lye, VIII., 209, 1865. It was named after 

 the Rev. E. C. BoUes, an enthusiastic con- 

 chologist, formerly curator of the depart- 

 ment of mollusca at the Peabody Academy 

 of Science, at Salem, Mass. 



It is a very rare shell and extremely local. 

 It has been quoted from Maine, New Hamp- 

 shire, Massachusetts, New York, Norfolk, 

 Va., and Tiverton, R. I. I have never 

 seen it in our state, but in Rehoboth about 

 three miles over the line in Massachusetts, 

 I have found it on stones and leaves abun- 

 dantly under a butternut tree b}- the side of 

 the road. About half a mile from this lo- 

 cality I found others under precisel}' the 

 same circumstances, but know of no other 

 spot where the3' can be obtained, save under 

 those two butternuts. The shell has four 

 whorls, amber colored, sub-translucent; 

 apex obtuse ; within the mouth are five teeth, 



one prominent and a little curved, on the 

 parietal wall ; two similar ones on the 

 columella margin, and two lamelliform, 

 elevated teeth at the base, within the aper- 

 ture. Size of shell sixt^'-five by thirty-five 

 one-thousandths of an inch. 



110. Vertigo (Al^a) Gouldii, Binney. 



Described by Binne}^ in Proc. Bost. Soc. 

 Nat. His., I., 105, 1843. It is of a light 

 chestnut color, with four and a half whorls 

 and five teeth resembling those of Bolles- 

 iana excepting that the two on the base 

 are not lamelliform and within the aperture, 

 but spring up from the labial margin and 

 are shaped like the other teeth. This species 

 is found under leaves in the woods and is 

 found throughout New England and the 

 Middle States. Length one thirty'- second, 

 breadth one sixty-fourth inch. 



111. Vertigo (Al.ea) Milium, Gould. 



Described by Dr. A. A. Gould (for whom 

 the previous species was named) in Jour., 

 Bost. Soc. Nat. Hist., III., 401, 1840. It 

 was first discovered at Oak Island, Chelsea, 

 Mass., in November, 1839, after a warm rain. 

 It is distributed from New England to 

 Texas, but is seldom observed on account 

 of its extreme minuteness, being even 

 smaller than Carychium exignum. It has 

 six teeth, two on the parietal wall, one on 

 the middle of the left lip, one on the base 

 of the aperture, and two on the outer lip 

 within the mouth. It has a large and deep 

 umbilicus, but four whorls, dark amber col- 

 ored, and is the smallest species of the genus. 

 "It is four one hundredths of an inch in 

 length, three one-hundredths in breadth, 

 and weighs five one-thousandths of a grain ; 

 and this tin}' shell incloses a pulsating heart, 

 a lung, stomach, liver, and all the organs 

 we find in the larger snails" (Morse). 

 Found under deca3'ing leaves in woods, and 

 sometimes under stones in pastures. Mr. 

 Thomson has found them in green moss 

 hanging from white oak trees. 



112. Vertigo (Al.ea) Ovata, Say. 



Described by Thomas Say in Jour. Acad. 

 Nat. Sci. Phila., II.. 375, 1822. Thin, 

 amber colored and highly polished ; whorls 

 five ; aperture semi-oval with from four to 

 eight teeth. There are generally two and 

 sometimes three on the parietal wall and 



