642 APPENDIX. 



Vol. ii. p. 22C. Genus HELICARION. 



The species II. flammnlata and viridis have been separated 

 by Dr. Gray as a genus, under the name of Vitrinella, but as 

 Vitrinella is already in use, we would suggest that of Otesia 

 in its place. 



Genus OTESIA, H. and A. Adams (Vitrinella, Gray, not 



C. B. Adams). 



Mantle-lobe covering the greater part of the shell. 

 Shell imperforate, very thin ; spire conic. 



Genus ORPIELLA, Gray. 



Dr. Gray has also constituted a genus under the above name 

 to receive Helicarion scorpio. 



Animal with the usual anal lappet of Nanina covering the 

 mucous pore, and six other smaller ones between this and the 

 shell arranged in a double series along the back of the tail. 

 Shell somewhat like Cyclostoma tigrinum. (Gould.) 



Ex. 0. scorpio, Gould, pi. 138, fig. 6. 



Vol. ii. p. 227. Fam. AEIONIDiE. 



To this family must be referred the genera Maricella and 

 Laconia, Gray, which are slug-like and have the shell partly or 

 entirely covered by the mantle, and in which the caudal gland is 

 present. 



Genus MARLELLA, Gray. 



Mantle or body convex, produced like a fleshy collar in front, 

 swollen behind, and separated from the upper part of the foot, 

 in a cavity of which it lies ; fringed on the side. 



