516 MAZATLAN UNIVALVES 



(Cantharus) Tritonidea gemmatus, H. fy A. Ad. Gen. i. 85. 



= Buccinum mutabile (pars), Vol. Voy. Yen. pi. 6. f. 2 e. 

 f. 2, 2a-c exclus. : (2 a, /3, are intended for the operculum, 

 which they do not resembLj. They are probably over- 

 wrought figures from a deformed specimen.) 



This species, figured by Kien. as the female of B. undosum 

 (teste Rve. in loc. sp. 55,) finds an E. Indian analogue in B. 

 Proteus, Rve. sp. 51. [?=B. Coromandelianum, (Lam.) Kien. 

 Icon. Conch, p. 37, no. 38, pi. 22, f. 85.] It is known at once 

 from the depressed variety of P. insignis, and from P. O3qui- 

 lirata, by the flatness of the upper whirls : and from the former, 

 by the sharpness of the spiral lirulse, 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 1 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 costse (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 strise. The last rib is much thickened, with a small 

 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 Pasciolaroid plait ; labium 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 dalnaged, 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. 1*42, '55,' ,', *7, 60. 



The smallest "52, '2, '28, 50. 



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. costse developed. 2457, 3 do. spiral lines 

 developed. 2458, 3 sp. shewing colour and repaired fracture. 

 2459, 12 normal opercula. 2460, 4 do. subovate. 



