570 MOLLUSCA. 
b. hegewischi. 
Cerithium varicosum, Valenciennes, in Humboldt’s Obs. Zool. ii. p. 253 (1833) ™. 
Cerithium (Potamides) hegewischi, Philippi, Zeitschr. f. Malak. 1848, p. 19"; Abbild. neuer Conch. 
iii. p. 15, t. 1. ig. 6%; Kobelt, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Cerithium, 
p. 64, t. 18. fig. 1 *7 (copied from Philippi). 
Potamis hegewischi, Carpenter, Report Moll. W. Coast of N. Am. p. 238 (1857) ™. 
Cerithidea varicosa, var. mazatlanica, Carpenter, List Mazatlan Shells, p. 344 (1857) °; Reeve, 
Conch. Icon. xv., Cerithidea, t. 3. fig. 195”. 
Cerithidea mazatlanica, Reeve, Conch. Icon. xv., Cerithidea, t. 1. fig. 8"; Carpenter, Moll. W. 
N. Am. pp. 108, 186 (1872) ”. 
Cerithium mazatlanicum, Kobelt, loc. cit. p. 161, t. 30. figg. 4, 5”. 
Potamides sacrata (A. Gould) (part.), Tryon, Manual of Conch. ix. p. 162, t. 33. fig. 70 (copied 
from Reeve) (not figg. 69, 71, 72)™. 
Smaller, only 33-34 millim, in length. Of the six spiral rows of knobs in the last whorl between the suture 
and the basal angle, the two upper ones are often smaller, disappearing entirely in some specimens, so 
that only four remain. According to Philippi, the ribs are more arcuated, thirty in number, and the 
varices of a milk-white colour. 
Hab. N.W. Mexico: Mazatlan (eigen 19 2°); Mexico, without nearer indication of 
locality (Hegewisch 1-1"). | 
W. GuatemMata: Champerico (Champion, Stoll). 
The Guatemalan specimens seen by me measure only 27-30 millim. in length and 
11-114 in diameter ; aperture 74-84 millim. 
N.B.—P. iostomus, Pfeiffer (Arch. f. Naturg. 1840), from Cuba, much resembles the 
smaller forms of this species, having also very conspicuous varices; but its sculpture is 
only ribbed, not latticed, and the shell is not so much attenuated above and dilated 
below as in P. varicosus *. 
* and Sowerby (Genera of 
* There is some difficulty regarding the name of this species: Valenciennes * 
Shells, part 42) each used the name Cerithium varicosum, apparently in the same year, 1833. Valenciennes 
gives a description only, without figure, and mentions as locality “‘Cumana”; he describes the sculpture as 
“ treillisée” (latticed), and therefore I have no doubt that he had before him the species of the western shore, 
not P. iostomus, Pfr., from the Caribbean coast. He gives the same locality, Cumana, for his Cerithium 
humboldti, Val. = Potamides pacificus (Sow.), a species inhabiting the Pacific coast. Sowerby, on the contrary 
(Genera of Shells, part 42, t. 259. fig. 5), gives only a figure, without description, and no indication of 
locality ; this figure is reproduced by Reeve (Conch. Syst. il. t. 126. fig. 9), and I am inclined to refer it to 
the West-Indian P. costomus, Pfr., from its size and appearance. In his later work, ‘ Thesaurus Conchyliorum,’ 
the greater part of the description and the first figure, 284, apply to the larger form of this species, fig. 281 
probably to P. albovaricosus, and fig. 282, without varices, to yet another species. 
Bayle’ has given a new name (C. fortiusculum) to Cerithium varicosum, Sow., on account of the latter 
being preoccupied (C. varicosum, Defrance, 1817), a fossil form; but in the genus Potamides or Cerithidea the 
name has not been used, so far as 1 am aware. 
