304 MAZATLAN BIVALVES 
specimens of this form approach Cerithium famelicum, from 
which it may always be distinguished by the row of very 
characteristic crenations along the suture, Sometimes the 
tubercles become rather obsolete, when it has the appearance 
of C. adustum, Sow. (non Aven). The adolescent shells have 
the mouth effuse and the canal straight. Of these very few 
specimens were sent. Afterwards the anterior canal is turned 
sharply back; the labrum being more or less pinched up at 
the base, so as somewhat to cover it. The large posterior 
canal is formed by the gradual advance of the labrum up 
the spire, pinched up opposite the stout labial callosity. The 
labrum is thin, and with the rest of the peritreme often stained 
with violet. The operculum is not large for the shell, with the 
nucleus sunken, and the few turns of spire scarcely seen out- 
side, but conspicuous in the muscular scar inside. The outer 
margin is smooth; the outer surface appears so, but under the 
microscope displays most minute strice in the direction of 
growth, still more minutely decussated into granules. The 
muscular scar is not corrugated asin Murex, but has very 
irregularly waved lines breaking up into cireular spaces. The 
smallest adult measures long. 1 05, long. spir. °63, lat. °4, div. 33°. 
A stumpy sp. A Su eleoo Z, 1ODs2 5, “66 eee: 
An elongated sp. ,, cpa bs "6820.4. cOSseim OO 
Hab.—Acapulco & Galapagos, Kiener.—Galapagos, Cuming.— 
Taboga; common in wet sand, under stones. at half tide 
level, C. B. Adams.—S. W. Mexico, P. P. C. —Mazatlan ; 
very common: L’pool §& Havre Coll. 
Tablet 1575 contains 3 sp. immature.—1576, 3 do. adult, dif- 
ferent sizes.—1577, 3 do. dwarf var. elongated.—1578, 3 do. do. 
swollen.—1579, 3 sp. light colour.—1580, 3 do. usual state.— 
1581, 3 do. dark tint.—1582, 3 sp. very nodulous, (one with 
opere.)—1583, 3 do. slightly nodulous, elongate.—1584, 3 do. 
with repaired fractures.—1585, 2 sp. one with the anterior, the 
other the posterior canal marked off by the abnormally indent- 
ed labrum.—1586, 9 opercula. 
* 
382. CreRITHiuM PFamMELicum, C. B. Ad. 
C. B. Ad. Pan. Shells, pp. 152, 309, no. 196, (pars.) 
=C. uncinatum (Gimel.) Sow. pars. Thes. Conch. pl. 180, f. 79. 
Var. MEDIOLEVE. C. 2famelicum, t. nitidd, epidermide sub- 
politd, striulis spiralibus haud tmpressis: serie tuberculorum 
