MAZATLAN UNIVALVES 475 
while that of P. pansa applies as exactly to certain small speci- 
mens of P. patula collected by Dr. W. B. Carpenter at St. 
Vincent’s, W. I. The magnificent shells brought by Mr. 
Cuming from the Philippines, are also quite indistinguishable 
from the Mazatlan type. Shell extremely variable; with the 
spire sometimes exserted as in P. columellaris ; sometimes 
flattened, or even decollated. It is commonly covered with 
Balani, and is also a favourite station of Acmeza mitella. Along 
with its parasites, it is frequently encrusted by a thin violet 
layer, apparently of corallinous growth. Operculum small for 
the size of the aperture, looking like a chip of rosewood out- 
side, within of a purple black : muscular scar large, with 
layers of growth, and the whole surface microscopically 
striated transversely. ‘The largest of the specimens mea- 
sures long. 3°24, long. spir. °64, lat. 2°22, div. 110°. 
Anelevatedsp. ,, 2°62, ay 203. 5. Ae 5s) a eeu 
A broad sp. etd, BZ TAA Ost ae eee 
Hab.—Senegal; on the rocks of Cape Manuel; Adanson.— 
Near Bonifacio, Corsica, Payraudeau.—Jamaica, Barbadoes, 
Piée, (Voyageur naturaliste de Muséum.) — St. Vincent’s, 
/W.I., W. B. Carpenter.—Philippines Is., Cuming.—Mazat- 
lan, Botfa :—Do.; not uncommon; L’pool Col. 
Tablet 2214 contains 5 sp. different ages, elevated spire.— 
2215, 9 sp. normal shape, (the largest with operc.)—2216, 3 sp. 
flattened.—2217, 3 do. decollated, one with scarcely more than 
one whirl left.—2218, 1 sp. shewing violet deposit, and mark of 
Acmeza mitella.—2219, 1 sp. after hot acid, inside with light 
band.—2220, one separate operculum. 
604. Purpura COLUMELLARIS, Lam. 
An. s. Vert. vol. x. p. 62, no. 4.—Eneycl. pl. 398, f. 3 a, b.— 
Blainv. Nouv. Ann. Mus. vol. i. p. 220, no. 40, pl. 10, f. 7.— 
Kien. Icon. Conch, p.78, no. 49, pl. 20, f. 58.—Schub. & Wagn. 
Chemn. p. 142, pl. 232, f. 4079-80.—Rve. Conch. Ic. pl. 2, 
sp. 9. 
Normal specimens of this shell are extremely different from 
P. patula, being small, extremely thick, with an elevated spire, 
granulated tubercles, mouth not open, (often contracted as in 
Nematura,) labium with a columellar fold as in Cuma tectum, 
labrum beautifully crenulated with black over a chesnut 
“ground, and furnished within with five (or six) stout tubercles. 
