MAZATLAN UNIVALVES 393 
460. DritiiIa RuUpDIS, Sow. 
Pieurotoma rudis, Sow. Proc. Zool. Soc. 1833, p. 134.—Miull. 
Syn. Nov. Test. Viv. p.109.—Rve. Conch. Le. pl. 7, sp. 53.— 
C. B. Ad. Pan. Shells, p. 146, no. ¥81. 
Crassispira (Drillia) rudis, H. & A. Ad. Gen. i. 91. 
Comp. P. excentrica, Sow. loc. cit.—Rve. loc. cit. sp. 58.— 
(Drillia e.) H. & A. Ad. Gen. i. 90. 
In a genus, the discrimination of whose species rests on 
minute details of sculpture, the figures in the Conch. Ic. are of 
but little help. The two shells from the Mazatlan boxes, with 
others obtained from a shop, probably from the same collection, 
agree in some points with each species, but are referred to 
D. rudis by Mr. Cuming. They are ofa dull black, without 
white spots, with the upper keel nodulous in the upper whirls, 
arow of costal tubercles abnormally shewing at the suture, 
with spiral lines faintly nodulous below; the whole surface 
minutely spirally striulated, more coarsely in the region of 
the notch; the last whirl descending and then rising, making 
the axis excentric; aperture ending in a notch with a very 
stout callosity rising above: labrum thin, slightly incurved 
and serrated, with a strong rib behind ; labium distinct. 
Long. 1°1, long. spir. °6, lat. 48, div. (apper whirls) 48°. 
Hab.—Monte Christi; under stones; Cuming.—Mazatlan ; 
extremely rare ; L’pool Col. 
Tablet 1890 contains one specimen. 
461. DRintia aTEeRRimMa, Sow. var. Mrencuerst. 
Pleurotoma aterrima, Sow. Proc. Zool. Soc. 1833, p. 137.— 
Mill. Syn. Nov. Test. Viv. p. 113.—Rve. Conch. Ie. pl. 12, 
sp. 100.—C. B. Ad. Pan. Sheils, p. 138, no. 163. 
Crassispira (Drillia) aterrima, H. & A. Ad. Gen. i. 90. 
P=PL maura, Val. in Kien. Icon. Conch. p. 59, no. 37, pl. 23, 
f. 1. (non Sow.) 
= Pl. Melchersi, Uke. i: in Zeit. f. Mal. 1851, p. 20, no. 91. 
P+ Pleurotoma Trace Sow. Proce. Zool. sca 1833, p. 137.— 
Mill. Syn. Nov. Test. Vin. p. 113.—Rve. Conch. Syst. pl. 235, 
f. 14:—Conch. Ie. pl. 6, f. 38. 
Var. ?=PI. atrior, C. B. Ad. Pan. Shells, no. 164, pp. 138, 308. 
= Pleurotoma rustica, P; P. C. Cat. Prov., non Sow. 
It is fortunate if Kiener’s species, described from a specimen 
brought from Mazatlan by M. Botta, is not needed, as the 
