'62 



RANDOM NOTES ON NATURAL HISTORY. 



The Shell-Bearing MoUusca of Rhode 

 Island. 



BY HORACE F. CARPENTER. 



Chapter XIX. 



Family 37. Melaniidae, comprises sev- 

 eral hundred species of /res/i water shells, 

 inhabiting all the warmer parts of the world 

 ■excepting North America. 



Family 38. Strepomatidoe, are also 

 fresh water shells, about five hundred 

 species, mosth' confined to the United 

 States, but not known to inhabit New Eng- 

 land. 



Family 39. Risscellidte, not repre- 

 sented in Rhode Island. 



Family 40. Rissoidie, contains an im- 

 mense number of species, inhabiting all 

 parts of the world, some genera in fresh 

 water, and others in salt water, while some 

 are amphibious. The animals are all herbi- 

 vorous. This family is divided into seven 

 sub-families, viz. : 

 Sub-Family 1. Bythinina^, two genera. 



" " 2. Skeneinse, one genus. 



" " 3. Rissoininffi, four genera. 



" " 4. Rissoinse, three " 



" " 5. Hydrobiinte, fifteen " 



" " 6. Lithoglj'phinae, six " 



" " 7. Pomatiopsinffi, one genus. 



Sub-Family 1. Bythininte, not repre- 

 sented in America. 



Sub-Family 2. Skeneinje, contains one 

 genus, Skenea, Fleming. Represented in 

 New England by one species. 



54. Skenea planorbis, Fabricus. 



Shell minute, flat, discoidal, deeply um- 

 bilicated, showing all the whorls, three in 

 number ; apex slightly elevated ; aperture 

 round, dilated, in contact with, but not 

 forming any part of the preceding whorl. 

 Length, one-twentieth of an inch, breadth 

 one-thirtieth. Habitat, on and under 

 stones at low water mark, on rockj- ocean 

 shores, and among the roots of our common 

 corallina. Dist., France and England, Nor 

 way, Spitzbergen, Iceland, Greenland, and 

 Labrador to Long Island Sound. 



Found in Rhode Island only at Watch 

 Hill, so far as now known. 



Sub-Family 3. Rissoininae, not repre- 

 sented on our coasts. 



Sub-Family, 4. Rissoinae, not repre- 

 sented in Rhode Island. 



Sub -Family 5. Hydrobiinse, contains 

 twelve genera, two of which, Littorinella 

 and Amnicola are represented in Rhode 

 Island. 



Sub-Families G and 7. Lithoglyphinae 

 and Pomatiopsinai are not found in Rhode 

 Island, although one species of Pomatiopsis 

 is found in the western parts of Massachu- 

 setts and Connecticut. 



Genus littorinella, Braun. 



Syns. : 



Paludinella, Loven (not Pfr.). Littorini- 

 dea, Eyd and Soul. 



Dist., World wide, in brackish or salt 

 water. 



55. Littorinella aculeus, Gould. 



Syns, : 



Cingula aculeus, Gld., DeKaj. 



Rissoa aculeus, Stimpson. 



Shell minute, ovate-c3lindrical, elon- 

 gated, light yellowish horn color ; whorls 

 six, separated by a deep suture ; apex ob- 

 tuse ; surface of the shell covered with regu- 

 lar microscopic revolving lines ; aperture 

 one-third the length of the shell, oval, ob- 

 lique ; lips simple, just touching the bodj' 

 whorl, leaving a small umbilicus. Length 

 three-twentieths of an inch ; breadth one- 

 fifteenth. Found on stones at low water 

 mai-k. It resembles the next species ver^- 

 much, but is distinguished b3' its habitat 

 and b}- the revolving lines. Long Island 

 Sound to Greenland. Common at New 

 Haven, Conn. (Verrill). Gull Island 

 (Smith). East Boston (Gld.). Watch 

 Hill, R. I. (Verrill). Whole New England 

 coast (Stimp.). 



56. Littorinella minuta, Totten. 

 Syns. : 



Turbo minutus, Totten. 



Cingula minuta, Gould, DeKa}'. 



Rissoa minuta, Gould, Stimp. 



Shell minute, ovate-conic, elevated, j'el- 

 lowish-green, usually coated with a dark 

 pigment or vegetable growth ; whorls five, 

 apex obtuse, suture distinct. Operculum 

 horny. The shape of the shell and of the 

 aperture, umbilicus and operculum is almost 

 exactly like those of the preceding species, 

 but the surface is destitute of revolving 

 lines and the breadth of the shell is one- 



