BYE: MOLLUSCA. 
| Morch, loc. cit. p. 87 ; Kobelt, t. 12. figg. 6, 7; Tryon, loc. cit. fig. 78 (original)], is 
a stouter shell, with a somewhat thicker peristome, but in other respects very similar, 
and these differences may be bridged over by examining a larger number of specimens. 
II. Ruinocoryne, v. Mart. 
5. Potamides pacificus. 
Cerithium pacificum, Sowerby, Genera of Shells, pt. 42, t. 259. fig. 9 (1833), = Reeve, Conch. Syst. 
ii. t. 126. fig. 9°; C. B. Adams, Ann. Lyc. Nat. Hist. N. York, v. p. 379 (1852) "s 
_ Carpenter, Report Moll. W. Coast N. Am. p. 825*; Kobelt, in Martini & Chemnitz, Syst. 
Conch.-Cab. ed. 2, Cerithium, p. 39, t. 8. figg. 5, 6°. 
Potamides pacificum, Morch, Malak. Blatt. vii. p. 80 (1861) °. 
Cerithidea pacifica, Reeve, Conch. Icon. xv., Cerithidea, t. 1. fig. L”. 
Cerithium humboldti, Valenciennes, in Humboldt’s Obs. Zool. ii. p. 280 (1833) **; Kiener, 
Iconogr. p. 83, t. 26. fig. 2°. 
Hab. S.W. Costa Rica: Punta Arenas, on Rhizophore (ersted; C. Hoffmann, in 
Mus. Berol.). 
S. Panama: Panama (Aiener®; C. B. Adams?, one specimen only). 
CotompBia: Tumaco (Hopke, in Mus. Berol.). 
N. Peru: Arica (Stiibel, in Mus. Berol.). 
Fam, LITTORINIDZ. 
Littorina is the only genus of this family entering within our limits; the various 
species are essentially submarine, living chiefly on rocks at high-water mark or on 
mangrove-shrubs. 
LITTORINA fF. 
Littorina, Ferussac, Tabl. Syst. p. xxxiv (1821) ; Menke, Syn. Meth. ed. 1, pp. 24, 25 (1828) ; 
Sowerby, Genera of Shells, part 37 (c. 1831); Deshayes, in Lamarck’s Hist. Nat. des Anim. 
sans Vert. éd. 2, ix. p. 200 (1843) ; Forbes & Hanley, Hist. Brit. Moll. iii. p. 25; Troschel, 
Gebiss d. Schnecken, i. p. 130, t. 10. figg. 13-20, t. 11. figg. 1-7 (radula), &e. 
Turbo (L.), sensu strictiore, Philippi, Enum. Moll. Sicil. p. 188 (1836) ; Swainson, Treatise Malac.— 
pp- 206, 207, 343 (1840). 
Shell turbinated, in most of the species ovato-conoidal, thick, acutely pointed ; 
aperture rounded below, angulated above, with broad flattened pillar-lip (area colu- 
mellaris); usually imperforate. Operculum horny, paucispiral. 
Living animal with projecting cylindrico-conical snout and long slender feelers, the 
* Valenciennes’s statement “ that the specimens described by himself were found in the port of Cumana 
(Venezuela) by A. v. Humboldt” is probably one of the many geographical errors in this work °. 
+ Some authors adopt Litorina and others Littorina for the name of this genus: philologically, both are 
admissible ; Férussac, however, wrote “ Zattorina,” and Linneus “ Turbo littoreus.” 
