CLASS GASTROPODA 
37 
Subgenus Pirenella Gray, 1847 
Potamides cyclus Dali, 1919 
Proceedings of the United States National Museum, 56:346. 
Shell small, white mottled with brown, probably darker when fresh, 
with six flattish whorls (excluding the lost nucleus) separated by a rather 
obscure suture; spiral sculpture of (on the spire and the upper half of the 
last whorl, three) rows of prominent hemispherical nodules, with subequal 
interspaces; on the lower half of the last whorl, four undulated or 
obscurely nodulose flattish cords with narrower interspaces; besides these 
there is fine spiral threading over the surface and in the interspaces; the 
nodules are arranged in vertical lines above one another and give the effect 
of ribs, but the ribs, if any, are very feeble and hardly perceptible in 
the interspaces; base rounded, aperture rounded, the outer lip slightly 
thickened, not internally lirate; body and pillar with a thick coat of enamel, 
pillar shorter than the aperture, with a sharp siphonal sulcus behind it. 
Height of shell, 6.5; of last whorl, 3.5; diameter, 3.5 mm. (Dali.) 
Type in United States National Museum, No. 215572. Type locality, 
Laguna Beach, California. 
Range. Long Beach, California, to Gulf of California. 
Subgenus Liocerithium Tryon, 1887 
Potamides sculptum Sowerby, 1855 
Thesaurus Conchyliorum, 2:868, figs. 144, 145. 
Cerith. testa parva, solida, vertricosa, fusco-nigrescente variegata, 
spiraliter costellis planulatis, crenulatis, et interstitiis linearibus cincta; 
anfractibus rotundatis, ultimo magno; apertura rotundata; canali breve; 
labio externo crenulato fimbriato. (Sowerby.) 
A small, solid, darkly variegated, grooved shell of a rather conical 
form, with rounded whorls. (Sowerby.) 
Type in British Museum? Type locality unknown. 
Range. Santa Barbara Islands, California, to Panama and Galapagos 
Islands. 
Described as Cerithium. 
Genus CERITHIDEA Swainson, 1840 
Shell turriculated, longitudinally ribbed; whorls numerous; summit of 
spire more or less decollated, aperture rounded, slightly slit anteriorly, 
outer lip expanded, thickened, broadly rounded below and usually pro¬ 
duced into a beak crossing the sinus to the left. Inhabit salt marshes, man- 
1639] 
