230 ACTHONIDH, AKERATID#. 
ADELACTZON Cossmann, 1895. 
Ess. Pal. Comp., p. 54, type A. papyraceus Bast., Miocene. 
Proposed as a substitute for Myonia A. Ad. non Dana, see Vol. 
xv, p. 167. Includes several Miocene species, the recent A. concinna 
Ad. (Vol. xv, p. 172) of Australia, and several Japanese forms (see 
Voliexv, p. 1695170): 

Genus KLEINELLA A. Adams (Vol. xv, p. 179). 
Cossmann, in his excellent Essais de Paléoconchologie Comparée, 
pt. 1, p. 44 (1895), has been able, by the assistance of Messrs. R. 
B. Newton and E. A.Smith, to figure the type of this genus, K. can- 
cellaris Ad., and to determine the fact that it does not belong to the 
Acteonide, but is allied to Menestho. His figure of K. cancellaris is 
reproduced in figure 6 of Frontispiece. For description see Vol. xv, 
p. 180. 
Acteon aplisiformis Fér., Tab. Syst., p. xxx= Elysia viridis Bose. 
Acteon viridis Fér. 1. c. (Laplysia viridis Mont.)=Elysia, a nudi- 
branch. 
Family AKERATID Pilsbry, (Vol. xv, p. 350). 
Genus AKERA (Vol. xv, p. 376). 
A. BULLATA Miller (Vol. xv, p. 377). 
Var. nana Jeffreys. Length ;% inch. 
Var. farrant Norman. Length 1? inch. (=A. bullata var. 
gigantea Norman, Mus. Normanianum, iv, Moll. 1888, No. 101). 
The variation in size in this species is most extraordinary, and 
perhaps the forms here treated as varieties should rather be regarded 
as entitled to rank as species. The full size of ordinary specimens 
may be taken as an inch; but no specimens of var. nana which were 
dredged by Jeffreys and myself in shallow water at Balta Sound, 
Shetland, exceed three-twentieths of an inch. On the other hand, 
Dr. Farran found many years ago (see Nat. Hist. Review, Vol. iv, 
[1857] p. 74) the gigantic variety which I here name after him. 
The specimens were dredged near Birterbuy Bay, Ireland; the 
animal measured 3 inches long and 23 wide, and weighed 22 ounces. 
The shell of one of these giants now in my collection measures 17 
inches long and an inch wide; hundreds of specimens of var. nana 
