352 MANUAL OF THE MOLLUSCA. 
Synonyms, Heterofusus, Fleming. Heliconoides, D’Orbigny. 
Peracle, Forbes. Seaea, Ph. . 
Shell minute, hyaline, sinistrally spiral, globose or turreted, 
smooth or reticulated; operculum thin, glassy, semilunar 
slightly spiral, with a central muscular scar. 
Animat with narrow, simple fins, united by a simple, trans- 
verse operculigerous lobe; mouth central, with prominent lips. 
Distribution, 12 species. Greenland and Norway to Cape 
Horn, Indian Ocean, Pacific. 
? CHELETROPIS, Forbes. 
Etymology, chele, a claw, and tropis, a keel. 
Synonym, Sinusigera, D’Orbigny. 
Type, C. Huxleyi, Pl. X1IV., 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- 
anuke. 
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, horny, 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 Janthina; lingual dentition closely resembling 
Jeffreysia. 
Distribution, 3 species. Taken in the towing-net off Capo 
Byron, East coast of Australia, 15 miles from shore, floating, 
and apparently gregarious. (J. Macgilliyray.) Mindoro, North 
Atlantic. (Adams.) 
