U2 



LAND AND mESII-WATER SHELLS OF X. A. [TART II. 



Alicylus sallei, Bourguipxat. — Shell convex anteriorly, posteriorly 

 rectilinear or slightly convex ; left side convex, right side rectilinear ; 

 posterior apex declining to the right, its summit obtuse so as to be quite 

 indiscernible. Shell small, very fragile, diaphanous, very finely radiated, 

 yellowish. Aperture oblong, IJ mill, high, 5 mill, long, 2 mill, broad. 



Found by Mr. Salle on fragments of decaying wood in the Laguna Larga 

 de Toxpam, near Cordova, Vera Cruz. {Bourguirjnat.') 



Ancijlus sallci, Boueguigxat, Mag. de Zool. 1857, 16. 



I have seen no specimens of this species. The original de- 

 scription is translated above. 



Alicylus parallelus, IIaldemax. — Shell pale, thin, and delicate ; 

 lengthened ; sides subrectilinear, diverging slightly forwards ; apex rather 

 slia|p, conspicuous, with two-fifths of the shell posterior to it. 

 Dimensions: Long. 0.25, lat. 0.15, elev. 0.08 inch (Adams). 

 Inhabits New England. 



In general appearance resembles Velletia larustris, Mil 11., of 

 Europe, but is at once distinguishable by having the apex di- 

 rected towards the right. Professor Adams remarks : " It was 

 •supposed to be Say's A. rii-uJai-is, not on account of any re- 

 semblance between the two shells, but from the meagreness 

 of the description. From some remarks of this learned naturalist, com- 

 paring A. rivularis with A. tai-duf!, it seems probable that the former is not 

 an elongate species." (Haldeman.) 



Alicylus parullehis, Haldeman, Mon. pt. 2, p. 3 of cover (1846) ; p. 11, 

 pi. i, f. 6 (1844).— Adams, Shells of Vt. 164 (1842).— DeKay, N. Y. 

 Moll. 13 (1843). 



Anrijlus rivularis, Gocld, Inv. of Mass. 224, f. 153 (1841), teste Halde- 

 man.— Anon. Can. Nat. IT, 212, fig. (1857). 



Dr. Gould's Ancylus rivularis is considered by Ilaldeman to 

 be this species and not A. rivularis, Say. 



Fig. 237. 



Ancylas 

 jmrallelits. 



AncylUS rivularis, Say. — Shell corneous, opaque, conic-depressed, 

 apex obtuse, nearer to and leaning towards, one side and one 

 end ; aperture oval, rathev narrower at one end, entire ; within 

 milk-white. Length one-foi\rth of an inch. Cabinet of the 

 Academy. 



Common ; adhering to stones in rivulets ; the animal re- 

 sembles the inhabitant of shells of the ger.us Limnaa, the 

 tail is very obtu.se, roumled. {■'^or/.) 



