= 
516 MAZATLAN UNIVALVES 
(Cantharus) Tritonidea gemmatus, H. § A. Ad. Gen. i. 85. 
= Buccinum mutabile (pars), Val. Voy. Ven. pl. 6. f. 2e. 
f.2, 2.a-c exclus.: (2, 8, are intended for the operculum, 
which they do not resemble. They are probably over- 
wrought figures from a deformed specimen.) 
This species, figured by Kien. as the female of B. undosum 
(teste Ave. in loc. sp. 55,) finds an EK. Indian analogue in B. 
Proteus, Rve. sp.51. [?=B. Coromandelianum, (Lam.) Kien. 
Icon. Conch. p. 37, no. 38, pl. 22, f. 85.] It is known at once 
from the depressed variety of P. insignis, and from P. equi- 
lirata, by the flatness of the upper whirls: and from the former, 
by the sharpness of the spiral lirule, which are black at the 
points. The epidermis is not quite so coarse; and beneath, 
the shell is of a prevailing black-brown, with more or less of 
white markings, especially a spot at the back of the last rib, 
near the suture. The three upper whirls are smooth: the 
succeeding ones flat, deeply pitted by the intersection of trans- 
verse and spiral ribs; suture not conspicuous. ‘The shells are 
rarely incrusted; and vary but little, in the elevation of the 
spire, and strength of the transverse coste (which are generally 
very obscure), and of the spiral lines. These are at nearly 
regular distances, except that the second below the suture is 
missed on the last two whirls. Between each are three or four 
fine spiral striz. The last rib is much thickened, with a smalt 
posterior canal bounded by a sharp parietal plait. The varix — 
is hollow at first, then filled up, and grooved within, ending 
in more or less sharp serrations at the margin. Columella with 
one slight Fasciolaroid plait ; labrum warty near the base, very 
slightly above. Mouth pure white, edged with black in the 
young state. Operculum like that of P. insignis ; but swollen, 
darker, without the olivaceous and internally yellowish tinge. 
The shells are rarely fractured, being very strong; but the 
opercula are frequently damaged, and when renewed are fre- 
quently ovate with the nucleus more or less central. The largest 
specimen measures long. 1.34, long. spir. ‘54, lat. *87, div. 70°. 
An elevated sp. 7) Le 42, LOD asada sO a 
The smallest age 2 Pe MR Mir ho beet NON 
Tablet 2452 contains 6 sp. young and adolescent.—2453, 7 sp. 
broad form.—2454, 6 do. normal form.—2455, 4 do. acuminated 
form.—2456, 2 sp. coste developed.—2457, 3 do. spiral lines 
developed.—2458, 3 sp. shewing colour and repaired fracture.— 
2459, 12 normal opercula.—2460, 4 do, subovate. 
