392 MAZATLAN UNIVALVES 
Hab.—W. Columbia; in sandy mud, 16fm.: Cuming.—Maz- 
atlan ; not uncommon; L’pool Col. 
Tablet 1882 contains 8 sp. different ages and markings.— 
1883, 3 do. colour scarcely developed.—1884, 4: sp. rather more 
slender.—1885, 4. sp. mended after fracture, (one with a fresh, 
separate canal.)—1886, 3 do. spire bent.—1887, 1 sp. pierced by 
a Proboscidifer.—Six of the above sp. have the normal opercula 
in situ; tablet 1888 contains 2 sp. with abnormal opercula in 
situ, and one normal operculum separate. 
Genus DRILLIA, Gray. 
Fig. Moll. An. p. 73, no. 3.—H. & A. Ad. Gen. vol. i. p. 89. 
Clavatula, pars, Zam. The operculum is Purpuroid in Clava- 
tula, Pleurotomoid in Drillia. Canal very short. The group 
is remarkable, among marine shells, for the number of black 
species. 
459. DRILLIA INCRASSATA, Sow. 
Pleurotoma incrassata, Sow. Proc. Zool. Soc. 1833, p. 138.— 
Mill. Syn. Nov. Test. Viv. p. 115.—Rve. Conch. Ic. pl. 9, 
f.76.—Mke. in Zeit. f. Maj. 1851, p. 19, no. 90.—C. B. Ad. 
Pan. Shells, p. 144, no. 175. 
Crassispira (Drillia) incrassata, H. & A. Ad. Gen.i. 91. 
Pleurotoma Bottx, Kien. Icon. Conch. p. 33, no. 26, pl. 15, f. 2. 
The solitary Mazatlan specimen differs from Kiener’s figure 
of M. Botta’s supposed unique shell, in being quite black, with 
the labrum serrated, sharp, and incurved at the edge, then 
very much thickened (‘18in.) ; behind very thin, nearly tran- 
sparent. Posterior callosity distinct. The aspect of the shell 
is like a very large D. luctuosa, with very fine granulose radia- 
ting lines, about 18 in a whirl. A closely analogous form 
from the W. Indies, is probably the D. gibbosa, Chem. ele- 
gantly figured by Mien. Icon. Conch. pl. 16, f. 2. as his own 
species ; the error being corrected by Rve. sp. 30. Long. 1°64, 
long. spir. °83, lat. °68, div. 30°. 
Hab.—Panama and Monte Christi; in sandy mud 6—10 fm. ; 
Cuming.— Panama, 1 sp. C. B. Adams.—Mazatlan, Botta :— 
do.; 1 fresh sp.; L’pool Col. 
Tablet 1889 contains the specimen. 
