852 MANUAL OF THE MOLLUSCA. 



Synonyms, Heterofusus, rieming. Heliconoidos, D'Orbigny. 

 Peracle, Forbes. Seaea, Ph. 



Shell minute, hyaline, sinistrally sj^iral, globose or turreted, 

 smooth or reticulated ; operculum thin, glassy, semilunar, 

 slightly spiral, with a central muscular scar. 



Animal with narrow, simple fins, united by a simple, trans- 

 verse operculigerous lobe ; mouth central, with prominent lips. 



Distribution, 12 species. Greenland and Norway to Capo 

 Horn, Indian Ocean, Pacific. 



? Cheletropis, Forbes. 



Etym.ology, chele, a claw, and tropisy a keel. 



Synonym, Sinusigera, D'Orbigny. 



Type, C. Huxleyi, PI. XIV., Fig. 43. 



Shell dextrally spiral, imperforate, double-keeled ; nucleus 

 sinistral ; aperture channelled in front ; peristome thickened, 

 reflected, with two claw-like lobes. 



Animal gregarious in the open sea. 



The species comprised in this and the following genus are 

 young gasteropods. (See pp. 212, 225.) 



Distribution, 2 species. South America and South-east 

 Australia. 



Another minute spiral shell may be noticed here : — 

 Macgillivrayia, Forbes. 



Named after its discoverer, the naturalist to H.M.S. Rattle- 

 snake. 



Type, M. pelagica, PL XIV., Fig. 44. 



Shell minute, dextrally spiral, globular, imperforate, thin, 

 horny, translucent ; spire obtuse ; aperture oblong, entire ; 

 peristome thin, incomplete; operculum thin, hornj^, concentric, 

 nucleus sub-external. 



Animal with 4 long tentacles, mantle with a siphonal process ; 

 foot expanded, truncated in front, furnished with a float after the 

 manner of lanthina ; lingual dentition closely resembling 

 Jeffreysia. 



Distribution, 3 species. Taken in the towing-net ofi" Capo 

 Byron, East coast of Australia, 15 miles from shore, floating, 

 and apparently gregarious. (J. Macgillivray.) Mindoro, NortJi 

 A-tlantic. (Adams.) 



