MAZATLAN UNIVALVES 465 



angle below the shoulder less conspicuous than in O. angulata. 

 The parietal teeth are either wanting or extremely minute ; 

 and the columellar plaits are generally white ; rarely slightly 

 tinted with purple or brown. The prevailing tint is as in the 

 W. Indian O. reticularis, which is a much more regularly 

 shaped shell. There are always a number of penciled lines 

 below the suture, sometimes irregular, sometimes gathered in 

 bundles or triangles. The colour-pattern shews a tendency to 

 triangulation, sometimes nearly hidden by a rich layer of dark 

 cloudy dots, (passing into O. angulata,) sometimes sharply 

 developed. The variations in painting are so great as to 

 require that a large proportion of the small stock sent should 

 be retained. Long. T82, long. spir. *42, lat. '82, div. 80. 

 Slab. Mazatlan ; very rare ; L'pool Col. 



Tablet 2111 contains 2 sp., with rich, lustrous brown mark- 

 ings ; triangulation indistinct. 2112, 2 do. ground lighter. 

 2113, 2 do. ground yellowish. 2114, 2 do. ground grey. 2115, 

 2 do. light, with faint markings. 



Tablet 2116 contains 2 sp., rich dark colour, triangulation 

 distinct. 2117, 2 do. ground lighter. 2118, 2 do. ground 

 orange brown. 2119, 2 do. markings flesh coloured. 2120, 

 2 do. zigzag lines separating. 



592. OLIVA INTEETINCTA, ?n. s. 



0. t. forma " O. Melchersi" simulante : sed multo minore ; 

 anfr. iii. nucleosis porcellanis, apice planato ; iv. normalibus, 

 spir a subelevatd ; inter trientem et dimidium totius longitudinis 

 obscure angulato ; spird parum callosd ; superficie alba, casta- 

 neo spar sim tenue maculatd, inter dum lineis irregularibus con- 

 Jluentibus ; labro intus ad marginem castaneo-fusco variegatd ; 

 pariete denticulatd ; plicis columellaribus omnibus castaneis. 



More than a score of specimens were found agreeing in the 

 above particulars, and not according with the young of any of 

 the other species ; of which however it may ultimately prove 

 to be a variety. It has the shape of O. Melchersi, but differs 

 in the dentition of the inner lip, and in the chestnut stain on 

 all the plaits, not on all but one as in O. venulata. Miss Steer e, 

 whose attention to this genus is well known, has a larger 

 specimen, which she had long considered as .distinct : another, 

 from an unknown locality, in my collection, confirms her judg- 

 ment. Long. *78, long. spir. "2, lat. "37, div. 70. 



