278 MOLLUSCA.—CLASS IV. PTEROPODA. 
Example. 
Pl. CCXCV. Fig. 3. 
LiMAcINA HELICIALIS, Sowerby, Genera of Shells, No. 39. 
Clio helicina, Gmelin. 
Argonauta Arctica, Fabricius. 
Spiratella limacina? De Blainville. 
CRESEIS, Rang. 
Testa conica, elongata, recta, diaphana, rosea, posticé acuminata; an- 
ticé aperta, parte dorsali longiori, sulco semitorto per totam lon- 
gitudinem decurrente. 
The genus Creseis, founded by Rang, includes certain others of the Pte- 
ropoda distinguished only by the conical formation of their shell ; they 
are said, indeed, to resemble the Hyalee so closely in other respects, 
that D’Orbigny refers them to that genus. Some authors have referred 
them to the genus Cleodora ; and Quoy and Gaimard, it will be seen on re- 
ference to our synonyms, have assigned them at different times to both. 
The shell of Creseis may be described as being conical, elongated, 
straight, diaphanous, and of a pale rose-colour ; posteriorly it is sharp 
and acuminated ; anteriarly it is open; and the dorsal side of the shell is 
longer, more pointed, and has a somewhat twisted groove running through- 
out its entire length. 
Example. 
Pl. CCXCV. Fig. 4. 
CRESEIS SPINIFERA, Rang, Annales des Sciences Naturelles, vol. xiii. 
pl. 17. f. 1. Quoy and Gaimard, Voyage de l’Astrolabe, pl. 27. 
f. 15 and 16. 
Hyalea subula, D’Orbigny. 
Cleodora subula? Quoy and Gaimard (Ann. des Sci.). 
Cleodora spinifera, Deshayes. 
