334 MAZATIAN 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, Soiv. (non Kie^). 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 striae in the direction of 

 growth, still more minutely decussated into granules. The 

 muscular scar is not corrugated as in Murex, but has very 

 irregularly waved lines breaking up into circular spaces. The 

 smallest adult measures long. l'Q5,long. spir, '63, lat. '4, div. 33. 

 A stumpy sp. 1'35, "65, '66 45. 



An elongated sp. T7, '68, '68,,, 30. 



Hob. 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 fy 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 

 operc.) 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. CERITHIUM ? FAMELICUM, C. B. Ad. 



C. B. Ad. Pan. Shells, pp. 152, 309, no. 196, (pars.) 



= C. uncinatum (Gmel.) Sow. pars. Thes. Condi, pi. 180, f. 79. 



Var. MEDIOL^EVE. C. ? famelicum, t. nitida, epidermide sul- 

 polita, striulis spiralibus haud impressis ; serie tuberculonim 



