340 MAZATLAN UNIVALVES 



operculum is on tlie same plan as in the Cerithia (proper) ; but 

 is larger in proportion, thin near the margin, rather concave, 

 with the spiral part saucer-shaped, bounded by a raised mar- 

 gin ; outer surface minutely granulated, more conspicuously 

 than in C. maculosum ; muscular scar small, with very few 

 undulating lines ; remainder of inner surface extremely glossy. 

 The smallest adult is 1'14 long ; the largest measures long. 1*45, 

 long. spir. 1*5, lot. *5, div. 25. 

 Hob. Panama ; in sandy mud, 2 or 3 7 + fm. j Hinds. 



Taboga ; very rare ; C. B. Adams. Mazatlan ; common ; 



L'pool Sf Havre Coll. 



Tablet 1605 contains a series of 5 sp. shewing the formation 

 of the adult mouth. 1606, 4 sp. adult, large and small. 1607, 

 7 sp. colour varying from light spotted, to uniform brown red. 



1608, 5 sp. shewing different positions of penultimate varix. 



1609, 5 sp. with irregularities of growth. 1610, 2 sp. with 

 opercula in situ, of which one is abnormal. 1611, 1 sp. with 

 operculum cut-off from the dead animal within. It is altogether 

 abnormal, irregularly formed of concentric elements, deeply 

 indented, and sculptured occasionally with a V pattern, with- 

 out granules. It may be the result of the same injury to the 

 shell which fractured the mouth and destroyed the upper 

 whirls. 1612, 4 normal opercula. 



390. VERTAGUS sp. ind* 



Tablet 1613 contains a fragment, of Cerithiopsoid aspect, but 

 with a distinct columellar plait. The whirls are short, numer- 

 ous, subquadrate, with two rows of coarse broad tubercles. 

 Hob. Mazatlan ; 1 sp, off Spondylus ; L'pool Col. 



GENUS TEIFOEIS, Desk. 



Enc. Meth. ii. p. 1053, 1830. Phil. Handb. Conch, p. 166. 



JET. # A. Ad. Gen. vol i. p. 287. 

 Cerithium, pars, auct. 



Shell reversed ; canals sometimes tubular ; operculum orbicu- 

 lar, few- whirled. This genus appears rare on the W. American 

 coast, from which there is not one among the many species 

 described by Hinds. Prof. Adams has described three, from a 

 few Panama specimens, which are here adopted with great 



