312 MOLLUSCA. 
regularly arcuated at the outer side, sinuous in the form of an S on the columellar side, rounded at the 
base; external margin thin, simple, arcuate; columellar margin formed by a strong, thick, white, spirally 
twisted line, which enters above into the interior of the aperture, and is terminated at the base by a 
vertical narrow notch. 
Length (of the injured shell) 11 millim., diam. including the aperture 3, diam. of the penultimate whorl 23 ; 
aperture 24 millim. long, 14 broad. Last whorl, seen from the dorsal side, one-third of the length of the 
six preserved whorls united. 
Hab. E. Guatemata: Panzos (Conradt). 
In the unique specimen the coste are rubbed down here and there, and the hole of 
the upper breach is open, which proves that the upper whorls have not been lost 
during life. 
LEPTINARIA. 
Achatina, subgen. Leptinaria, Beck, Ind. Moll. p. 37 (1837). 
Bulimus, subgen. Nothus, Albers, Die Helic. ed. 1, p. 168 (1850) [preoccupied in Coleoptera by 
Olivier (1811) and in Lepidoptera by Billberg (1820) ]. 
Leptinaria, Shuttleworth, in Mittheil. nat. Ges. Bern, 1854, Diagn. neuer Moll. no. 6, p. 144. 
Cionella, subgen. Leptinaria, v. Martens, in Albers’s Die Helic. ed. 2, p. 254. 
Lamellaxis, Strebel, Beitr. Mex. Land- und Siissw.-Conch. v. p. 109 (1882). 
Shell ovate or oblong, mostly perforate or umbilicate, thin, semipellucid, whitish, 
with feeble vertical strie; whorls 5-8, rather convex, increasing considerably in 
diameter (much more than in Opeas and Subulina) ; aperture oval or oblong; columellar 
margin distinctly twisted and notched near the base of. the aperture in the form of a 
more or less distinct fold or tooth, mostly expanded outwards and covering a part of 
the perforation. In some species (Group B) an additional fold or spiral plate on the 
upper wall of the aperture (parietal plate). 
Jaw thin, somewhat arcuate, with fine vertical strie. Teeth of the radula in straight 
transverse rows, the median tooth very small, the lateral ones tricuspidate. See 
Fischer and Crosse, Journ. de Conch. v. p. 241 (1857), and Miss. Scient. Mex., Mollusca, 1. 
p. 622; Gibbons, in Binney’s “ Notes on the Jaw and Lingual Dentition of Pulmonata” 
(Ann. Lyc. N. York, iii. p. 101). Anatomy of the genital organs not yet known. Some 
species are said to be viviparous, but in others there are to be seen globular eggs of 
rather large size (Tab. XVIII. fig. 7), resembling those of Sudulina. 
A generic distinction between those with and those without parietal plate cannot be 
maintained, because in some species this plate is very conspicuous in young shells and 
disappears nearly or entirely in full-grown ones, as, for instance, in Z. stolli; in others 
it is not seen in young shells, but well in full-grown ones, as in L. emmeline. 
The species of this genus are very closely allied and difficult to determine. In 
many cases it is almost impossible to say whether a specimen is full-grown or young. 
The comparative differences, too, in the general outlines, in the strength of the 
sculpture, and in the shape of the columellar margin (inner edge of the aperture) are 
very gradual, and it may well be doubted if the various authors, including myself, 
mean the same when speaking of strong or fine costa, of strie, &c., and in describing 
