CLASS GASTROPODA 
51 
Larval shell polished, with swollen apex. Diameter about 2 m. (Trans¬ 
lation.) 
Type in Cuming Collection. Type locality, imbedded in the surface of 
a young Haliotis. 
Range. Forrester Island, Alaska, to San Diego, California. 
Genus PETALOCONCHUS Lea, 1843 
Animal ignotum. Operculum (speciebus ii.) parvum, corneum, dia- 
panum, tenuissimum; anfractibus paucis, vix apparentibus. Testa extus 
Bivoniae similis; intus transversim rarissime septata; anfractibus medianis 
laminis elongatis spiralibus varie dispositis, cameram saepe secantibus; 
plerumque duabus, plica columellari una. 
Shell of corkscrew growth, glomerate, or single, affixed by one side of 
the whorls; earlier and later whorls open; middle whorls divided by spiral 
laminae, often of complex structure, which gradually pass away at each 
end; generally two, nearly meeting, with a third rudimentary, forming a 
columellar plait. (Lea.) 
Example. Vermetus sculpturatus Lea. 
Distribution. Mare Mediterranean; Oceanum Atlanticum, Pacifi- 
cum, Indicum. 
Petaloconchus anellum Morch, 1861 
Proceedings, Zoological Society of London, 359. Tryon, Manual of Conchology, 
8: 173; PI. 49, fig. 34. 
T. sinistralis, Candida, spira affixa, spirorbiformis, umbilico aperto; 
anfr. pauci, ultimus solum adspectabilis, rapide crescens, peripheria dila- 
tata, costis transversis acutis valvidis, leviter flexis; apertura soluta, subo- 
valis, latere interno dilatato, recto, superne et inferne angulo recto. Diam. 
testae fere, 3)4 m.; aperturae, 1 m. (Morch.) 
Shell sinistral, spirorbiform, white, spire affixed, umbilicus open, 
whorls few, with transverse close ribs. Diameter of shell about 2 to 
3.5 mm. (Tryon.) 
Type in British Museum ( ?). Type locality, California on Haliotis. 
Range. Monterey, California, to Todos Santos Bay, Lower Cali¬ 
fornia. Described as Vermctis; in United States National Museum, Bulle¬ 
tin 112 , as Vermiculum annellum. 
Petaloconchus macrophragma Carpenter, 1857 
Masatlan Catalogue, 309. Tryon, Manual of Conchology , 8: PI. 48, fig. 16. 
P.t. parva, dextrali, dense purpureo-fusca; cylindracea, solute spirali, 
marginibus spirae saepe subparallelis; plerumque glomerante, interdum 
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