MAZATLAX TJNIVAIVES 495 



Buecinuin luteostoma, Kien. Icon. Conch, p. 110, pi. 30, f. 1. — 

 Eyd. ^ Soul. Voy. Bonite, pi. 41, f. 5-7 :— -B. M. Cat. p. 25, 

 no. 203. 



Nassa santliostoma, Gray in Zool. Beech. Yoy. 1839, p. 127, 

 pi. 36, f. 3 -.—Fuj. Moll. All. pi. 85, a, f. 5. 



(Nassa) Phrontis xanthostoma. El. df A. Ad. Gen. i. 118. 



Tills abundant shell is sometimes of a nearly uniform brown ; 

 sometimes striped with, light ; sometimes of a uniform yellow- 

 ish, brown. The yellow colour of the characteristic broad flat 

 labium varies in intensity, being sometimes very slight. The 

 spire varies somewhat in amount of acumination. The oper- 

 culum is irregularly triangular, with two rounded sides, sharply 

 serrated ; the apex being lateral, and turned against the 

 anterior wave in the labrum ; the third side, being convex and 

 smooth, against the labial portion. The vertical angle varies, 

 and the serrations are more or less close, (sometimes as many 

 as 15,) obsolete towards the apex. A large number of opercula 

 were foimd more or less abnormal ; the apex being more or 

 less internal, as in Buccinum, with the serrations either absent, 

 or very few in number. The muscular scar occupies the 

 basal portion. The smallest of the adult specimens mea- 

 sures long. '6, long. spir. '2, lat. '43, div. 55". 



An acuminated sp. „ "88, „ "4, „ '56, „ 50°. 



An ordinary sp. „ '87, „ "38, „ "62, „ 60". 



JSah. — Eeal Llejos and Acapulco, Lesson in Rev. Zool. Aug. 

 1842. — [Senegal, Kiener, ?err. — Australia, Metcalf in B. M. 

 err.]— Panama ; 330 sp. on sand, usually not far below high 

 water mark, in places where water is running during the 

 recess of the tide ; also in similar places not far above low 

 water mark ; C. B. Adams. — Mazatlan ; extremely abun- 

 dant ; L'pool Sf Savre Coll. 



Tablet 2366 contains 5 sp. young. — 2367, 5 do. lip forming. — 

 2368, 5 do. nearly mature. — 2369, 5 sp. lip light coloured. — 

 2370, 7 do. normal state. — 2371, 3 do. lip dark. — 2372, 3 sp. 

 spire acuminated. — 2373, 5 sp. shewing colour of back. — 2374, 

 5 do. after acid treatment. — 2375, 4 sp. mended after fracture. — 

 2376, 3 sp. dwarf variety. — 2377, 2 sp. with opercuJa in situ. — 

 2378, 12 normal opercula. — 2379, 5 do. abnormal, irregular. — 

 2380, 4 do. ovate, or with one prong. — 2381, 3 do. with two or 

 three prongs.— 2382, 4 do. with three or four prongs.— 2383, 

 3 do. with four or five prongs on each side. 



