460 MAZATLAN UNIVALVES 
Mitra lens, Rve. Conch. Ic. pl. 1, f. 1.—Mke. in Zeit. f. Mal. 
1851, p. 35, no. 120.— C. B. Ad. Pan. Shells, p. 42, no. 17.— 
HT. & A. Ad. Gen. i. 169. 
Tiara foraminata, Swains.ms.; Brod. Proc. Zool. Soc. 1835, 
p. 194. 
Mitra Dupontii, Kien. Icon. Conch, p. 43, pl. 13, f. 39. 
This species varies very much in growth and sculpture ; but 
is almost always recognized by the deep punctures which occur 
at irregular distances in the middle of the whirl, causing tuber- 
cles to rise up within. Between these are numerous broad 
ecoste, 8—13 in awhirl, more or less obsolete in the adult. 
These are crossed in the young shell, by numerous fine, more 
or less sharp spiral ridges ; which at varying periods of growth 
become rounded and finally obsolete. At the same time 
unpressed spiral lines often appear, connecting the pits. When 
adult, the columella has 3 plaits, with a fourth underneath, 
rudimentary. In the young shell this is absent; and the third 
is often rudimentary, rarely absent. The shell is covered with 
a smooth, close, dark olive or brownish epidermis; and is 
generally densely incrusted with coralline. Underneath it is 
of an ashy brown, sometimes light, sometimes very dark. The 
largest sp. measures long.2°4, long. spir. 1°34, lat. 94, div. 30°. 
A broad sp. ,, Set es iy. ass On; 78, ak Os eevee, Due. 
A narrow sp. ., Pd Ae "8, j48O4,  .; 30°. 
Hab.—Panama, St. Elena, and Is. Plata; in sandy mud, 
6—14fm.; Cwming.—Panama, very rare, C. 'B. Adams.— 
La Paz, Major Rich—Mazatlan ; not uncommon; L’pool & 
Havre Coll. 
Tablet 2091 contains 4 sp. elongated form.—2092, 5 sp. nor- 
mal state.-—2093, 4 sp. broad.—2094, 7 sp. shewing changes of 
sculpture.—2095, 2 sp. after acid process, shewing colour.— 
2096, 1 sp. curiously eroded.—2097, 1 sp. with egg-cases. 
Tablet 2098 contains a young specimen, strongly and 
closely sculptured, but without pits. Deeply cut lines however 
appear, in which the pits would probably have afterwards 
appeared. 
Tablet 2099 contains a small acuminated sp. without pits, 
costee narrow and distant, spiral sculpture nearly obsolete, 
columella biplcate. Were it not for the great variation in the 
ordinary specimens, this would have been regarded as a dis- 
tinet species. 
