468 MAZATLAN TTNIVALVE3 



Voluta tenebrosa, (Mawe) Wood, Ind. Test. Suppl. pi. 4, f. 38. 

 OUveUa iindatella, ff. Sf A. Ad. Gen. i. 146. 

 Comp. Oliva zonalis, Mke. in Zeit.f. Mai. 1847, p. 183, no. 25 ; 

 non Lam. 



Tliis species varies, as usual, in tlie elevation of spire and 

 the comparative breadth ; but its principal changes are in 

 colouring ; passing from pure white to rich piu'ple or more 

 usually with zigzag or undulating markings, pink on a white 

 ground, or, (normally) with various shades of dark olive. The 

 spiral band occupies more or less of the back, at a greater or 

 less angle. Although the animal remained in many of the 

 specimens, sufficiently fresh to swell out in water, no trace 

 of operculum was found. The largest of the specimens 

 measures long. '68, long. spir.'lS, lat.'Z, div. 70". 



A broad sp. „ "61, „ '16, „ '29, „ 80". 



Hab. — Acapulco, Humholdt Sf JBonpland. — Panama ; in sand 

 and on mud banks at low water ; Cuming. — Do. very rare, 

 C. B. Adams. — Mazatlan ; common; L'pool Sf Havre Coll. 



Tablet 2138 contains 5 sp. pure white.— 2139, 5 do. slight 

 markings of pink. — 2140, 5 do. pink markings stronger.— 2141, 

 •5 do. well developed.— 2142, 5 do. markings fine and close. — 

 2143, 5 do. pink passing into olive. 



Tablet 2144 contains 5 sp. white with rare spots of olive. — 

 2145, 5 do. olive spots more developed. — 2146, 5 do. with broad 

 white band. — 2147, 5 do. olive markings undulating.— 214S, 

 5 do. zigzag. — 2159, 5 do. passing into general olive. 



Tablet 2150 contains 5 sp., undulations absent or very faint ; 

 gray with white spiral band.— 2151, 5 do. spiral^ band dark, 

 gray passing towards purple. — 2152, 5 do. dark purple. — 2153, 

 5 do. purple changing into olive. — 2154, 5 do. lighter. — 2155, 

 5 do. dark olive changing into light. — 2156, 5 do. light olive. 



Tablet 2157 contains 5 sp., undulations more or less distinct ; 

 olive tinged with orange. — 2158, 5 do. max kings light, faint 

 olive.— 2159, 5 do. more distinct.— 2160, 5 do. distinct.— 2161. 

 5 do. dark olive. — 2162, 5. do. white groundwork appearing. — 

 2163, 5 do. white in larger spots. — 2164, 5 do. colour darker. — 

 2165, 5 do. rich olive. — 2166, 5 do. shading into purple. 



Tablet 2167 contains 4 sp. mended after fracture, colour 

 changing. — 2168, 3 sp. shewing variations of form. — 2169. 2 do. 

 spiral band varying. — (In all, 154 sp. with an appreciable dif- 

 ference between every two.) 



