PHYSA. 361 
a. Long. 20, diam. 10; apert. long. 142, lat. 6 millim. 
b.  , 193, ” 9; ” 14, 9 53 9 
¢. » 1%, ” 9: ” 123, 9 53 ” 
d ”? 17, ” 8 3 ” 13, ” 43 ” 
All the measurements from specimens from the same locality. 
Hab. N.W. Costa Rica: Laguna Redonda, near Candelaria (C. Hoffmann, 1856, in 
Mus. Berol. *). 
Of this form there are numerous specimens in the Berlin Museum. 
Var. pliculosa,n. (Tab. XX. figg. 11, 11a, 12.) 
Physa aurantia (Carp.), Biolley, Moluscos terr. y fluv. de Costa Rica, p. 17 (part.)}*. 
Somewhat larger than the type, with very distinct broad vertical plaits on the last whorl. 
a. Long. 193, diam. 11; apert. long. 15, lat. 6 millim. 
9 19, ” 10; ” 14, ” 53 ” 
ce 4 17, 4 10; ” 13, ,, 53 
d. ” 17, ” 93; ” 13, 9 5 
29 17, 99 8 3 99 11, 99 53 99 
a-d. Measurements taken from specimens from the same locality, Reventazon River; e. Specimens from the 
Rio Torres. 
Hab. Cuntrau Costa Rica: in all the rivers near San José, as Virilla, Torres, Maria 
Aguilar, and Tiribi, and in all smaller streams, by which it is carried into every 
pool during the rainy season; also at Cartago, and in the Rio Reventazon, at 
Ujarras (Biolley +); Costa Rica, without nearer indication of locality (Van Patten, 
in Mus. Berol.). 
S.W. Costa Rica: Picada de “ Senaba,” probably in error for Terraba (fulton). 
This form often shows spiral scratches on the outside of the last whorl; these are 
also mentioned in Morelet’s diagnosis of P. fuliginea, but they are not visible in all 
specimens, even in some of those obtained from Morelet himself. Some examples 
have a large number of scratches extending over nearly the whole of the last whorl, 
from the suture to the base. In the varieties from Costa Rica they are present only 
in the minority of specimens and not very numerous. 
According to a MS. note by Biolley, the var. pliculosa is found on stones, in a strong 
current, in the Rio Torres. 
6. Physa cisternina. 
Physa cisternina, Morelet, Test. Noviss. ii. p. 15 (1851) 1; Biolley, Moluscos terr. y fluv. de Costa 
Rica, p. 177. . 
Aplecta cisternina, Fisch. & Crosse, Miss. Scient. Mex., Mollusca, ii. p. 94, t. 30. fig. 7 °, 
Rather variable in outline, of dull brown colour, spire broadly conical; aperture widened below, columellar 
margin thick, callous, purple or brownish, rather short, turning arcuately into the basal margin. 
a. Long. 23, diam. 11; apert. long. 15, lat. 6 millim. 
Bs gg By we 8S ; 12, ,, 44 ,, 
a. Morelet’s specimen ; b. One of Biolley’s specimens. 
BIOL. CENTR.-AMER., Terr. and Fluviat. Mollusca, October 1898. 46 
