498 MOLLUSCA. 
by the spiral sculpture (which is more distinct near the periphery and on the 
lower side), its solidity, and the very oblique, oval (not circular) aperture. Moreover, 
the form of the operculum and radula is quite different, resembling that of the 
Hydrobiine. y 
Hitherto known from Ca/sfornia and Central America. 
) 
Y ANY 
—_ 
o 
CoMPARATIVE TABLE OF THE SPECIES OF CocHLIOPA. 
| Nomen. Forma. Sculptura. Umbilicus. Apertura. Diam.; Alt. | Anfr. Patria. 
mm. | mm. 
| guatemalensis, depressa. subtiliter decus- | angustus. marg. non con-| 33 23 42 | W. Guatemala. 
Morel. ......... sata, tinuis. 
tryoniana, Pilsbr..| obtuse subconica, | spiratim sulcata. | latus, rotundatus. | marg. callo junc- | 4-54 | 33-43] 4-43 | W. Nicaragua, | 
angulata. tis. S.W. Costa Rica. 
trochulus, v. Mart.) trochiformis, sulcis spiralibus | sat angustus, sub- ” d-6 | 45 42 | S.W. Costa Rica. 
carinata. parum conspi- | angulatus. 
cuis vel nullis. 
? infundibulum, | gradatim pyrami-| spiratim sulcata, | perspectivus, an- , marg. continuis. 3 4 5 | Guatemala. 
v. Mart. .:....... data,peripheria; sub sutura ra- gulatus, valde 
rotundata. diatim incisa. sulcatus. | 
1. Cochliopa guatemalensis. 3 
Valvata guatemalensis, Morelet, Test. Noviss. ii. p. 22 (1851)'; Fisch. & Crosse, Miss. Scient. 
Mex., Mollusca, 11. p. 802, t. 48. figg. 2, 2a, 6, t. 50. fige. 1, la, 6”. 
Hab. W. GuaTemaLa: River Michatoya, near the port of Istapa (Morelet }?). 
I have not seen a specimen of this shell, but, according to the description and figure, 
it is so much like the following in general form and sculpture, and in the outlines of 
the aperture, that it must belong to the same genus, if not to the same species; it 
seems, however, to be smaller and more flattened. 
2. Cochliopa tryoniana. (Tab. XXIII. figg. 9, 9 a-c.) 
Cochliopa tryoniana, Pilsbry, in Nautilus, iv. p. 52 (Sept. 1890)’; Proc. Acad. Phil. 1891, p. 331, 
t. 15. fig. 12°, 
Shell subconical, convex above, flattened below, more or less distinctly angulated at the periphery ; many fine 
spiral furrows on both faces, which do not, however, modify the convexity; colour greenish-brown ; 
whorls 4-43, separated by somewhat deep sutures; umbilicus open, its walls falling in gradually, so that 
no distinct external limit of it can be made out. Aperture diagonally oblique, narrowed above, pear- 
shaped; outer margin thin, somewhat convexly projecting, inner (columellar) margin thickened near the 
insertion and united with the insertion of the outer margin by a conspicuous glossy callus ; interior of the 
aperture bluish. . , 
Diam. maj. 4-53, min. 33-44, alt. 33-43 ; apert. diam. 3, alt. obliqua 4 millim. 
Hab. W. Nicaracua: Realejo, near Leon (Mus. Berol.); Polvon and Rio Fula 
(Hetlprin 2). | | 
S.W. Costa Rica: Great Range between the Rio Grande and Boruca, Novy. 1891 ; 
