464, MAZATLAN UNIVALVES 
Conch. Ic. pl. 1, f. 1—Mke. in Zeit. f. Mal. 1851, p. 23, 
no. 101.—C. B. Ad. Pan. Shells, p. 48, no. 32. 
Voluta incrassata, Dillw. Descr. Cat. p. 516, no. 35, 1817.— 
Wood Ind. Test. pl. 19, f. 35. 
_Strephona (Dactylus) incrassatus, H. & A. Ad. Gen. i. 143. 
The few specimens sent of this fine species were soon secured 
by collestors. They vary in amount of angulation and eleva- 
tion of spire, and in the pattern of the very characteristic dark 
blotches. A broad specimen, shoulder flattened and angle 
developed, measures Jong. 2°3, long. spir. *22, lat. 1°18, div. 110°. 
A slender sp. scarcely angulated, Jong. 2°45, long. spir. °3, 
lat. 1°19, div. 100°. 
Hab.—Peru, Deshayes.—Panama, very rare, C. B. Adams.— 
Gulf Nicoya; in sandy mud, 9fm.; Cuming.—Bay of Mag- 
dalena, Duclos: 24°5° N.[?]|—Mazatlan ; extremely rare: 
LT’pool & Havre Coil. 
Tablet 2110 contains the broad sp. 
591. Ottva Metcuersi, Whe. 
Zet. f. Mal. 1851, p. 24, no. 104. 
Oliva angulata, jun. P. P. C. Cat. Prov. 
Comp. Oliva subangulata, Phil. Abbild. 
Comp. O. Cumingii, Ave. ‘Conch. Ic. pl. 11, sp.19, (Gulf of 
California, Capt. Donnel.) 
Comp. O. polpaster, Ducl. Guér. Mag. Zool. 1839, pl. 20:— 
Rve. Conch. Ic. pl, 14, £.29: var. (Bay of Montija, sandy 
mud, 13 fm. Cuming.—Panama, Duclos.) 
The Mazatlan shells of the reticularis type divide themselves 
with tolerable facility into two sets, of which one answers 
in the main to the description of Menke (too minute however 
to include the whole group), and the other appears to be the 
O. venulata of Menke and Prof. Adams. In another collec- 
tion were found several distinct varieties of the latter. The 
discrimination of these from each other and from O. reticularis 
is a matter of extreme difficulty ; which Mr. Reeve escapes by 
uniting them all together. As the Pacific and Atlantic shells 
however have a different habit, it seemed right for the present, 
in so difficult a genus, to keep them apart. 
The shells here grouped are intermediate in character be- 
tween O.angulata and O. venulata. They are smaller than 
the former, larger than the latter ; with an acute spire, and an 
