340 MAZATLAN UNIVALVES 



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

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

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

 ajin ; 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". 



Hab. — Panama ; in sandy mud, 2 or 3 — 7 + fm. ; 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 dififerent 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, irregidarly formed of concentric elements, deeply 

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

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

 shell which fractured the mouth and destroyed the upper 

 whirb. — 1612, 4 normal opercula. 



390. Veetagus sp. ind. ^ 



Tablet 1613 contains a fragment, of Cerithiopsoid aspect, but 

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

 ous, sul)quadrate, %^Tth two rows of coarse broad tubercles. 

 Hah. — Mazatlan ; 1 sp. off Spondylus ; Upool Col. 



Gekus TEIFOEIS, Desh. 



Enc. Mefh. ii. p. 1053, IS'iO.— Phil Handh. Conch, p. Iti6.— 

 H. ^ A. Ad. Gen. vol i. p. 287. 



Cerithium, pars, auct. 



Shell reversed ; canals sometimes tubular ; opereidum orbicu- 

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

 I'oast, from which there is not one among the many species 

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

 r>'w Panama specimens, which are here adopted with great 



