LIMNAA. 375 
LIMN AAA. 
Buccinum, Geoffroy, Traité somm. de coquilles de Paris, p. 70 (1767); O. Fr. Miiller, Hist. Verm. 
li. p. 126 (nec Linn.). . 
Lymnea, Lamarck, Syst. d’Anim. sans Vert. p- 91 (1801). 
Limneus, Draparnaud, Tabl. Moll. Terr. et Fluv. de France, p: 47 (1801). 
Limnea, Desmarest (1814), etc.; Fischer & Crosse, Miss. Scient. Mex., Mollusca, ii. p. 38. 
Shell dextrally spiral, longer than broad, with acute, more or less prominent, spire ; 
aperture oval, with spirally twisted columellar margin. Feelers broad, triangular. 
Radula with very small median tooth and bi- or tricuspidate laterals. 
Cosmopolitan, more numerous in the temperate than in the tropical zone. 
1. Limnea attenuata. 
Limnea attenuata, Say, in New Harmony Disseminator of useful knowledge, ii. p. 244 (1829) °; 
ed. Binney, p. 48*; Hald. Monogr. Limniades, iv. p. 28, t. 9. figg.1-5°; Kiister, in Martini 
& Chemnitz, Syst. Conch.-Cab., ed. 2, Limneus, p. 39, t. 7. fig. 8°; Binney, Land and 
Freshwater Shells N. Am. ii. p. 42, figg. 53-55°; Sowerby, in Reeve’s Conch. Icon. xviii., 
Limnea, t. 18. fig. 832c°; Strebel, Beitr. Mex. Land- und Siissw.-Conch. 1. p. 57, t. 5. 
figg. 82, 32a"; Fisch. & Crosse, Miss. Scient. Mex., Mollusca, i. t. 27. figg. 11, lla, 6, 
ii. p. 49°; Pilsbry, Proc. Acad. Phil. 1891, p. 320°. 
Omphiscola pugio, Beck, Index Moll. p. 110 (1837) (sine descr.) ”. 
Limneus subulatus, Dunker, in Kiister, Martini & Chemnitz, Syst. Conch.-Cab., ed. 2, Limneus, 
p- 24,4. 4. fig. 24 (1862) "; v. Mart. in Malak. Blatt. xii. p.58 (1865) ; Clessin, in Martini 
& Chemnitz, Syst. Conch.-Cab., ed. 2, Limnziden, p. 395, t. 16. fig. 1”. 
Limnea emarginata (Hald.), Sowerby, in Reeve’s Conch. Icon. xviii., Limnea, t. 6. fig. 35”. 
Limneus turritus, Philippi, in coll. Dunker”. 
Limneus mexicanus, Ziegler, in coll. Dunker *. 
Hab. Cenrran Mexico: in ditches and ponds in the vicinity of the city of Mexico 
(Say1?24; Deppe & Schiede™); Mexico city, in plenty, in company with Physa 
mexicana and Planorbis tenuis (Uhde!®); Lake of Mexico (Dunker'!); Lake of 
Chalco (Strebel’, Heilprin®); Zimapan in Hidalgo (David, in coll. Dunker **). 
The locality “ Massach.” (Massachusetts) given by Sowerby 6, and by Patel in his 
Catalogue (1889), is of course incorrect. 
In its very elongate slender shell this species closely resembles some forms of the 
European ZL. palustris and of its North-American congener L. reflexa, Say; but it may 
be distinguished from both of them by the relatively narrower and less convex upper 
whorls, the penultimate one included, which contrasts generally by its slenderness with 
the more convex and sometimes inflated last whorl. The general colour, also, of the 
Mexican shell inclines to yellowish-brown, whereas in the European and North-American 
