358 CYLICHNIDA. 
fold in the inner lip, which is in the middle, flattened and pro- 
jecting in the space of the aperture, being separated from. the 
fold by a deep insinuation; the outer lip is generally somewhat 
produced anteriorly, the anterior canal, being distinct. Cre- 
taceous. &: decurtata, Sowb. 
? STOMATUDON, Seely, L861.» Described from a cast in the Cam- 
bridge Greensand. May be a Ringicula. #. polita, Seely. 
CINULIA, Gray. 
Disty.—25 sp... Cretaceous; Europe, United States. C. 
globulosa, Desh. (Ixxxviii, 58). 
Shell globose, spire short, surface spirally suleated, aperture 
anteriorly produced, effuse, columella terminating with a single 
oblique and twisted fold. 
ouicoprycuA, Meek. Shell with spire much depressed and 
obtuse; outer. lip smooth within, and. very slightly sinuous ‘at 
the base of the aperture; inner lip bearing a single, very promi- 
nent, nearly transverse plication or tooth at the base of) the 
columella. Actxon concinnus, Hall and Meek (1xxxviii, 59). 
AVELLANA, d’Orb. Shell globose, inner lip with two or three 
folds, one being anterior, often. bipartite, placed at. the termina- 
tion of the columella, ithe other subanterior, separated from. the 
former by a deep insinuation of the lip; there.is generally a 
third one placed about the middle of the inner lip, and one or 
two posterior, much shorter ones, but these are not constant. 
A. incrassata, V’Orb. (Ixxxviii, 60). 
Famity CY LICHNID2. 
Shell external, spiral, more or less cylindrical, usually white. 
No operculum. Animal with depressed quadrangular head ; 
truncated in front; bilobed behind; with eyes at the base of 
tentaculiform lobes; foot rather narrow, truncated in front. 
Teeth, central none, laterals 6-6, the inner large and hooked, the 
outer small and uniform, rarely wanting. 
Cyiicuna, Loven. 
Syn.—Bullina, Risso. 
Distr.—40 sp. Chiefly deep-water shells. United States, 
Greenland, Britain, Red Sea, Australia. Fossil. Triassic—. 
C. arachis, Quoy (1xxxvii, 30). 
Shell. strong, cylindrical, smooth or punctate-striate ; spire 
minute or truncated; aperture narrow, rounded in front; colu- 
mella callous, with one plait. 
MNEsTIA, H.and A. Adams. Shell oval, subcylindrical, banded, 
with revolving strie; aperture narrow, prolonged into a point 
at both ends. C. marmorata, A. Ad. (Ixxxvii, 31). 
CYLICHNELLA, Gabb. Shell subeylindrical, spire sunken ; mouth 
