MAZ1.TLA.N 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 Acmsea mitella. Along 

 with its parasites, it is frequently encrusted by a thin violet 

 layer, apparently of corallinous growth. Operculum small foi 

 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. 

 An elevated sp. 2*62, '93, 1*5, 60. 

 A broad sp. 2'34, '44, 1'9, 110. 

 Sab. Senegal ; on the rocks of Cape Manuel ; Adanson. 

 Near Bonifacio, Corsica, Payraudeau. Jamaica, Barbadoes, 

 PUe, (Voyageur naturaliste de Museum.) St. Vincent's, 

 W. I., W. B. Carpenter. Philippines Is., Cuming. Mazat- 

 lan, Botta : 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 

 Acmaea mitella. 2219, 1 sp. after hot acid, inside with light 

 band. 2220, one separate operculum. 



604. P0RPUEA COLUMELLABIS, Lam. 



An. s. Vert. vol. x. p. 62, no. k.Encycl pi. 398, f. 3 a, . 

 Blainv. Nouv. Ann. Mus. vol. i. p. 220, no. 40, pi. 10, f. 7. 

 Kien. Icon. Conch, p. 78, no. 49, pi. 20, f. 5SSckub. # Wagn. 

 Chemn. p. 142, pi. 232, f. 4079-80. Eve. Conch. Ic. pi. 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. 



