RANDOM NOTES ON NATURAL HISTORY. 



39 



from any generous reader of Random 

 Notes, who has them to spare. 



Genus Strobila, Mouse, 1864. 



Shell umbilieated, globose, conic, or de- 

 pressed, obliquely and coarsely striated, 

 smoother below ; aperture lunutely rounded ; 

 peristome thickened and reflected ; the pa- 

 rietal wall and base of the last whorl each 

 with two or more revolving laraelhe. Dis- 

 tribution, four species. United States, Mex- 

 ico, West Indies. Set apart from Helix as 

 a new genus, by Prof. Edward S. Morse, in 

 Jour. Portland Soc. Nat. Jlist., i., 20, 1864. 



92. Strobila Labyrinthica, Say. 



This shell was described by Say in May, 

 1817, in the Jov.rn. Acad. Nat. Soc. Phila., 

 Vol. I., p. 15. His description is not ex- 

 actly correct in several particulars. 



It belongs to a genus containing but four 

 species, two of which are represented in the 

 United States : one found only in one county 

 of Texas, and the one under consideration, 

 which inhabits all of eastern North Amer- 

 ica. 



It is of the same size (one-tenth of an 

 inch in height and breadth) and general ap^ 

 pearanee as Conulus chersina, described in 

 the February number of Randoh Notes ; 

 a globose conic shell with six volutions. It 

 differs from that species in having a small 

 umbilicus, in having oblique lines or ribs at 

 regular distances, distributed over its sur- 

 face, instead of being smooth and polished 

 as in chersina ; the outer lip is thickened 

 and reflected, and in fresh specimens has a 

 beautiful rose tint ; within the aperture on 

 the inner lip, are seen two parallel lamellar 

 teeth, running far back into the interior of 

 the aperture, and resembling a miniature 

 railroad track ; farther within the aperture 

 is a third line, only slightly raised, between 

 the other two. Under the microscope, these 

 three lamellar teeth are seen to be sur- 

 mounted with numerous sharp spines point- 

 ing toward the aperture. It is extremely 

 common in Rhode Island under leaves and 

 is also found on the under side of chips in 

 damp places. 



All the other genera of this immense fam- 

 ily of land shells, including among others 

 Bulimus, 323 species, Bulimulus, 545 spe- 

 cies, Buliminus, 350 species, are absent from 

 our fauna. 



Family Orthalicidic, thirty-two species, 

 inhabit the West Indies and tropical Amer- 

 ica. 



Family Achatinidae, sixteen genera and 

 over five hundred species is represented in 

 Rhode Island by the 



Genus Zua, Leach, 1820. 



" Shell ovate-oblong, imperforate, smooth, 

 pellucid, glistening, dark horn color ; 

 whorls rather convex ; aperture less than 

 half the total length of the shell, ovate ; 

 columella more or less truncated ; peristome 

 blunt, its margins joined by a callus." 



Woodward's Manual of the Mollusca gives 

 the number of species of Zua as six ; 

 Tyron recognizes nine ; Morse two, and 

 Binney but one, which inhabits all the 

 northern portions of Europe, Asia, and 

 America. This species was named Helix 

 subcylindrica by Linne in 1767, and is de- 

 scribed in European works on conchology 

 under fifteen different specific names. 



Morse observes a great difference in the 

 lingual dentition between the American 

 and European specimens, and considers our 

 shell to be a distinct species. I have col- 

 lected in Rhode Island, and also in the 

 grounds of the Crj^stal Palace at Sydenham, 

 Eng., and I can certainly see a difference in 

 the appearance of the two shells. Our 

 species is called 



93. Zua Lubricotdes, Stimp. 



It is a beautifully transparent, highh' pol- 

 ished, cylindrical shell, the size of a grain 

 of wheat, one-third of an inch long, smoky 

 horn color ; whorls six, rounded ; aperture 

 oval ; lip thickened and of a claret tint when 

 fresh. It is so highly polished that when one 

 attempts to pick one up, it slips out of the 

 fingers. It is ver}' plenty in some places, 

 though extremely local. Sa}- found it on the 

 shores and islands of Lake Winnepeg and 

 the Lake of the Woods. Gould found it at 

 Oak Island at Chelsea, Mass., in incalculable 

 numbers. It inhabits New England, New 

 York, Michigan, Nebraska, Canada, and 

 British America. I find it only in one local- 

 ity in Rhode Island, under a thick bed of 

 leaves, on the east side of a stone wall, near 

 the Mesodon thyroides locality in Cumber- 

 land. 



(To be contimied.) 



