MAZATLAN UNIVALVES 387 
portion which probably belongs to this species, though it ap- 
pears more slender. Long. 1°22, long. spir. °96, lat. *25, div. 13°. 
Hab.—Mazatlan ; extremely rare; Z’pool Col. 
Tablet 1838 contains the shell and the spiral fragment. 
Genus SUBULA, Schum. 
Subula, Schum. Hss. 1817, pars.—Distinguished by having the 
eyes on the tips of the tentacles, instead of on their outer 
bases ; in the shell, by the absence of the spiral band, 
sinuated lip and canal. 
Acus (Humph.) Gray, 1847, Proc. Zool. Soc. 1847, p. 139.-- 
Hf. &§ A. Ad. Gen. vol.i. p.224.—Comp. Gray, Gen. Moll. 1856. 
Terebra (pars) auct. 
454. Susuta Luctuosa, Minds. 
Terebra luctuosa, Proc. Zool. Soc. 1843, p. 157.— Hinds in Sow. 
Thes. Conch. p. 181, no. 89, pl. 45, f. 12].— Menke in Zeit. 
F. Mal. 1851, p. 34, no. 119. 
Hastula (Acus) luctuosa, H. & A. Ad. Gen. i. 225. 
Shell nearly related to S. cinerea and S. strigilata from 
the K. Indies. Lustrous, with extremely fine, crowded spiral 
strie, generally consisting of minute dots ; and very numerous, 
fine, slightly waved, sharp ribs on the upper part of the whirls, 
evanescent in the middle. Between these are often extremely 
minute radiating striule. About 6 of the first whirls are 
translucent and without ribs. Apex submamillary. First 
normal whirls with ribs strong. Outline very acuminate and 
nearly rectilinear. The outer lip when perfect, which it rarely 
is, is gracefully sinuated posteriorly in the direction of the 
ribs. About half the specimens are of an ashy or olivaceous 
brown ; the remainder of a lustrous brown black, often fading 
into light blue ; with scarcely any intermediate shades. Highly 
coloured specimens are sometimes found of a very dark olive 
green, with a row of infrasutural spots of purplish brown, 
sometimes over a yellowish green ground, occasionally con- 
fluent. The operculum is small, thin, horny, ovate, with faint 
waves of growth: its apex is terminal. The largest of the speci- 
mens, (making allowance for the tip which is broken off,) 
measures long. 1°84, long. spir. 1°4, lat. °33, div. 12°. 
A. broad sp. ip L362, sg ISEB... 5) (Aaa eae 
An attenuated sp. ,, 1°37, bi 103,);,:) °26; eee 
