258 MASATLAN UNIVALVES 
Genus NERITINA, Lam. 
Beritellg, Bumph.—H. & A. Ad. Gen. voli. p. 380. 
328. NeRITINA CASSICULUM, Sow. 
Couch. Hl. £. 55.—Thes. Conch. p. 521, no. 47, pl. 115, f. 194.— 
lMke. in Zat. f. Mal. 1850, p. 116, no. 19.—H. & A. Ad. Gen. 
1, 382. 
Comp. N. faba, Sow. Thes. Conch. p. 530, no. 78, pl. 115, f. 219— 
221.—Coneh. Lil. £.10.—(=Clithon f. H. & A. Ad. Gen. i. 
385.) 
Comp. Neritina Californica, Rve. Conch. Ie. pl. 4, sp. 20, f. 20, 
a, b. (Gulf of California, Mus. Cuming.) 
Although picked specimens may be found so far distinct 
from N. picta that Messrs. Adams have placed them in differ- 
ent subgenera, individuals may be found in each species so 
nearly alike that it is not impossible that they may ultimately 
prove to be identical.* They display exactly the same varieties 
# form, although they are much more constant in colour. The 
ifferences observed are as follows. This species is larger ; 
mouth white and stained with orange; inner lip rather flat- 
tened; teeth smaller and more irregular, more resembling 
those of N. virginea; operculum longer, with broader dark 
border, richer orange colour within, and medial line scarcely 
marked, If N. faba does not differ more than is stated in 
Sow.’s description, it may prove identical. He characterizes it 
as resembling N. picta, but having ‘“‘the spire rather more 
hidden, and the columella neither swelled [?swollen] nor of a 
chesnut colour.” It belongs however to another genus, teste 
H. §& a. da Whether these and connected species in the 
Pacific oe realry distinct from N. virginea with its many-named 
varieties from the Athantic, it must be for these to judge who 
have examined large series from different localities. The form 
exists in the B. M. from China, Philippine Is., and Port Essing- 
ton. Itis found on the coasts of Spain and reaches Dalmatia. 
A regularly formed sp. measures long. °68, lat. °83, div. 120°. 
A flattened ‘, LOLs OR i aia ee 
An elevated of PAR Riba io a rrteme Aion are e880) 
* As such I have freely distributed specimens. It is not unlikely that Prof. 
Adams regarded them as the same. ‘‘The specimens which Lieut. Green col- 
lected are of extraordinary size.” Pan. Snrells, p. 207. 
