PHYSA. 365. 
three specimens from Mazatlan contained in the Berlin Museum the columellar margin 
shows a very short umbilical slit at the under end of its outward expansion of the body- 
whorl, just as in P. panamensis and P. osculans; and that the last whorl, even if 
measured on the side of the aperture to the next upper suture, does not attain £ of the 
length of the whole shell, but only 3 or between 3 and & (in Binney’s figure > between 
$ and 8, and in Fischer and Crosse’s figure * $), or measured on the dorsal side ? of the 
whole length or a little less. 
This species is very nearly allied to P. (Aplecta) peruviana, Gray [*Spicilegia 
Zoologica,’ i. p. 5, t. 6. fig. 10 (1828)], from swamps between Lima and Callao, which, 
judging from specimens collected by Tschudi in Peru, has the same pale colour, but is 
of smaller size and has a comparatively somewhat longer spire: long. 16, diam. 7; 
aperture scarcely 11 millim. 
9. Physa panamensis. (Tab. XX. fig. 8.) 
Physa panamensis, Megerle v. Miihlfeldt, in Anton’s Verz. der Conch. p. 49 (1839)1; Kiister, in 
Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Limneaceen, p. 11, t. 2. figg. 8-6’. 
Shell lanceolate-ovate, rather solid, finely striated and moderately glistening, very pale yellowish, with a few 
brownish lines of growth, a little more opaquely whitish at the suture; spire acute; whorls nearly six, 
the uppermost dark reddish-brown, distinct, slightly convex, the last one seen from the dorsal side four- 
fifths the length of the shell, cylindrical in its middle part, distinctly more attenuated at the base thau 
above near the suture ; aperture a little more than two-thirds of the length of the shell, narrow obovate- 
lunate, rather narrowly rounded at the base; a broad, very distinct callus on the body-whorl, continued 
downwards into the broad reflexed outward expansion of the columellar margin, fully appressed to the 
body-whorl, and leaving only a minute slit at its under end; columellar margin unicolorous, white, 
straight in its greater part, forming a very obtuse angle with the convexity of the body-whorl, and with 
its lower end bending obliquely towards the basal margin. 
Long. 174, diam. 8; apert. long. 13, lat. 5 millim. 
Hab. Panama? 2, 
I have fortunately been able to examine Anton’s! typical specimen of this species, 
now in the Zoological Museum of Dresden. It is very like P. edata at first sight, but 
differs, on closer inspection, by the less glossy surface and the paler yellowish colour 
of the shell, the cylindrical (not elliptical) form of the middle part of the last whorl, 
and the much more conspicuous callus. The first and third differences may, perhaps, 
be due to the circumstance that the type of P. panamensis has been preserved in a dry 
state for at least 59 years, and it may have lost its natural lustre, the callus thus 
becoming more visible ; but the difference in form cannot be explained in this manner. 
From P. peruviana, Gray, it distinctly differs in the remarkably shorter and broader 
columellar margin. In the Berlin Museum there are some very similar specimens 
from Brazil, which were collected by Moricand in the Province of Bahia; the locality 
“ Panama,” therefore, seems to require confirmation. 
