129 AMERICAN MARINE CONCHOLOGY. 
six, last large, with a very obscure keel; axis umbilicated, keeled 
on the edge. 
Diam. 10 mill. 
Arctic Seas. 
Genus SPIRIALIS, Eydoux and Souleyet. 
Rey. Zool., 235. 1840. 
1. S. Gountpr, Stimpson. Fig. 254. 
Proc. Bost. Soc. Nat. Hist., iv. 8. 1851. 
Heterofusus balea, Binney (not Moller), Gould’s Inyert., edit. ii. 505. 1870. 
Shell ovate-globose, vitreous, very thin, pellucid, very light, 
narrowly and deeply umbilicated; spire conoid; whorls seven, 
sculptured by minute, distant, unimpressed, revolving lines; last 
whorl large; aperture about equalling the spire, obtuse in front. 
Length 2.5, breadth 1.8 mill. 
Mussachusetis Bay. 
2. S. ALEXANDRI, Verrill. Fig. 255. 
Am. Journ. Sci., 3d ser. iii. 281. 1872. 
Heterofusus retroversus, Binney (not Fleming), Gould’s Invert., edit. ii. 
505. 1870. 
Spirialis Plemingii? A. Agassiz (not Forbes), Bost. Proc., x. 14. 1865. 
Body-whorl very ventricose; spire of four whorls, not forming 
half the length of the shell. 
Nahant, Mass. 
Family CLIONID#, Gray. 
Syn. Brit. Mus. 1840. 
Genus CLIONE, Pallas. 
Spicil Zool., x. 28. 1774. 
1. C. nrmactnA, Phipps. Fig. 256. 
(Clio.) Voy. North Pole, 195. 1774. 
Clio borealis, Brug. Encyc. Meth. Vers., i. 506. 1792. 
Gelatinous, pellucid, pale-blue; mouth and end of the body 
scarlet when out of water, hyaline; wings somewhat triangular ; 
tail acute. 
Portland, Me., northwards. 
Cuass ACEHPHALA. 
Animal without head, always aquatic, contained within a bi- 
valve-shell, one valve of which is applied to the right and the 
other to the left side of the body. 
