MAZATLAN UNIVALVES 333 



FAMILY CEEITHIAD^E. 

 GENUS CEEITHIUM, Adans. 



Cerithium, Adanson, pars. H. fy A. Ad, Gen. vol. i. p. 284. 

 Shell with short, scarcely recurved canal ; columella not 

 plicated ; paries callous ; operculuni Littorinoid, thick. 



\ 381. CEEITHIUM MACULOSUM, Kien. 



Kien. Icon. Conch, p. 36, no. 25, pi. 13, f. 3, (non 2.) Lam. 



An. s. Vert. vol. ix. p. 312, no. 4&.Mbe. in Zeit. f. Mai 



1850, p. 178, no. 39. (Non Vertagus niaculosus, Martyn.) 

 Cerithium adustum, (Kien. teste fig. non diagn.) C. B* Ad. 



Pan. Shells, p. 150, no. 193. P. P. C. Cat. Prov. 

 Cerithium nebulosum, Sow. Thcs. Conch, sp. 71, pi. 179, f. 60. 

 ? + (var.) Cerithium adustum, Sow. loc. cit. sp. 70, pi. 178, f. 48. 



(Non Kien. diagn. et f. 2.) 



ICiener accurately described the Mazatlan shell as C. macu- 

 losum, but unfortunately in his plate named it C. adustum ; his 

 diagnosis of that species (loc. cit. p. 37, no. 26, f. 2 non 3 

 Lam. An. s. Vert. ix. p. 313, no. 46) being apparently intended 

 for a Red Sea shell. Sowerby (following Desk, and Mice.} cor- 

 rects the error of the plate, but alters both the species. He 

 changes the name of this to C. nebulosum, because as he 

 describes the whole family as one genus, he finds this term 

 preoccupied: and he affiliates C. adustum to a Galapagos 

 shell, which is probably only a smooth variety of the present 

 species. The figure is indeed coloured orange brown; but 

 that tint is not mentioned in the description, which accords 

 sufficiently well with the Mazatlan shell. An analogous species 

 is C. Guinaicum (Phil.) Sow. from Ld. Hood's Island. 



The Mazatlan species has the first 8 whirls flat, with a 

 divergence of 43, and sculptured with about 15 very faint 

 transverse ribs, crossed by about 5 rather strong lirulae. Here 

 and there a varix is formed. Afterwards the costse change 

 into a row of stout tubercles, rather above the middle of the 

 whirls, sometimes with a few rows of smaller ones on the body 

 and base of the shell. The spiral lirulse become very faint, 

 and are marked by lines of brown broken up into dots. Some- 

 times there are large patches of blackish brown ; sometimes 

 the prevailing hue is light. The shell is generally very broad 

 and gibbous ; but sometimes it is elongated. The dwarf 



