338 MAZATLAN UNIVALVES 



the different development of the tubercles on the same whirl, 



the axis has occasionally a bent appearance. Gould's type 



appears to have been rubbed smooth and faded. The opercu- 



lum is not large for the shell, and closely resembles that of 



C. maculosuni. The nucleus however is not sunken; the 



surface is not minutely striated, the outer margin is irregularly 



indented, and the markings of the muscular scar are coarser. 



The upper whirls are few in proportion, with the same diver- 



gence as the adult. Long. 1'4, long. spir. '8, lat. '66, div. 4D e . 



Sab. Acapulco, Humboldt fy JBonpland. Panama & Taboga ; 



at and above half tide level ; mostly in the margin of water 



left in the rocks by the tide ; very common, C. B. Adams. 



Gulf of California and Galapagos, Sowerby, (Mus. Cuming.) 



S. W. Mexico, P. P. C. Mazatlan; abundant; L'pool Col. 



Tablet 1593 contains 7 sp. different ages, elongated. 1594, 



8 sp. do. broader. 1595, 3. sp. adult ; of which one (dead) has 



marine attachments. 1596, 2 sp. lob-sided. 1597, 2 do. pale 



state. 1598, 1 sp. with operculum. 1599, 1 sp. with mended 



fracture. 1600, 2 sp., one with Balanus, the other bored by a 



Proboscidean ; extremely rare. 1601, 9 opercula. 



4- 388. CERITHIUM INTERRUPTUM, Mke. 



Cerithium interruptum, Mke. in Zeit f. M^al. 1850, p. 178, 

 no. 41. C. B. Ad. Pan. Shells, no. 198, p. 153. (Non 

 Cerithium interruptum, Lam. An. s. Vert. vol. ix. p. 328, 

 no. 1. Fos. Grignon.)* 



? -1- Cerithium - , sp. ind. C. S. Ad. loc. cit. no. 199. 

 Comp. Cerithium (Tympanotonus) Galapaginis, A. Ad. in Sow, 

 Thes. Conch, p. 869, no. 85, pi. 182, f. 155-6. 

 This species agrees exactly with both the figure and the 

 diagnosis of C. Galapaginis, but that shell is classed with Tym- 

 panotonus, with which this has no connection. It begins with 

 three smooth whirls, which soon fall off: then a few in which 

 the sculpture is wholly in spiral lirse, of which ojae just above 

 the suture is stronger, angulating the periphery ; at this stage 

 the base is scarcely notched, and the shell closely resembles 

 Trichotropis : afterwards the angular ridge subsides, the spiral 

 lines 'become granulose and the whirls somewhat rounded, 



* Should this imperfectly characterized shell prove to belong to the same genus, 

 Menke's name must be altered. If C. Galapaginia be identical, that may b<? 

 retained. If not, it may, according to custom, take the name of C. Menkei, 



