368 MOLLUSCA. 
12. Physa bullula. 
Aplecta bullula, Crosse & Fisch. in Journ. de Conch. xxix. p. 334 
Mollusca, ii. p. 91, t. 39. figg. 6, 6a, 5”. 
Hab. E. Mexico: Toxpam, State of Vera Cruz (Sallé } 2). 
Very nearly allied to P. sowerbyana, d’Orb., from Cuba, Jamaica, Puerto Rico, and 
St. Thomas, and to P. rivalis, Maton (1807), from the mainland of South America. Not 
having Mexican specimens at hand, I am unable to point out any reliable differences. 
(1881) *; Miss. Scient. Mex., 
13. Physa obtusa. (Tab. XX. figg. 7, 7a.) 
Physa obtusa, Clessin, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Limneiden, p. 292, t. 42. 
fig. 3°. 
Ovate, yellow, rather solid, with very short spire and rather thick twisted columellar margin; suture white ; 
a few white scratches near the base of the last whorl. 
Long. 13-14, diam. 7-8; apert. long. 104, lat. 5 millim. 
Hab. Honpuras (Hjalmarson'). 
Through the kindness of S. Clessin, I have been enabled to examine the original 
specimens of this species; it comes near P. bullula and P. sprculata, but differs from 
both in the remarkably shorter spire, the stronger, distinctly twisted columellar margin, 
the more intense yellow colour, and the solidity of the shell. 
Subgen. ALAMPETIS, n. 
Shell not so glossy and shining as in P. fontinalis, and more solid, with convex 
whorls; apex sometimes eroded ; margin of the aperture often thickened internally. 
Indented edges of the mantle and teeth of the radula as in typical Physa. Eggs 
deposited in kidney-shaped masses, sometimes on shells of the same species. 
The Mexican and some North-American species of Physa differ from the typical forms 
of this genus in the dull surface of the shell, contrasting strikingly with the glossy 
appearance of P. fontinalis. As the indented mantle-edges and the pectinated teeth 
of the radula have been found by myself to be present in P. berendti and P. mexicana, 
and the last-mentioned character in P. sgualida by Fischer, these species cannot be 
referred to Jsidora, in which genus the surface of the shell is also dull (not shining), 
the radula is quite differently formed, and the mantle is without indentations. ‘The 
kidney-shaped form of the egg-masses has been noticed in P. heterostropha by Haldeman 
(Monogr. Limniad. no. vi. t. 1. fig. a), in P. strebeli by Strebel (Beitr. Mex. Land- und 
Siissw.-Conch. i. t. 6. fig. 27), and in P. berendti by myself; whereas in P. fontinalis 
(cf. C. Pfeiffer, Land- und Siissw.-Moll. Deutschlands, i. t. 8. figg. 1-3) the egg-masses 
are flat and oval in form; in P. (Aplecta) hypnorum, L., however, they are also kidney- 
shaped (cf. C. Pfeiffer, l.c. t. 7. figg. 24-27). 
To this subgenus also the North-American Physa ancillaria, Say, may be referred. 
