MAZATLAN UNIVALVES 297 
Tablet 1462 contains an extremely young sp. with the helicoid 
apex.—1463, 2 young sp., one on Byssoarea solida.—1464, 1 sp. 
with exterior beautifully perfect.—1465, 2 sp. one very flat, 
the other very conical.—1466, 2 distorted sp. of which one is 
shaped like Amathina, Gray.—1467, 1 sp. probably old, with 
the margin narrowed inside hy non-serrated lamine. —1468, 
3 sp. shewing basal supports on the outside. 
347. Hipponyx ANTIQUATUS, Linn. 
Patella antiquata, Linn. Syst. Nat. p. 1259.—Gmel. p. 3709.— 
Mont. Test. Brit. p. 485, pl. 13, f.9.—Dillw. Deser. Cat. 
p. 1035, no. 44. 
=Lepas alba, Mart. Conch. pl. 12, f. 111-2 
+ Patella Mitrula, Gmel. p. 3708. 
+ Patella nivea, Gimel. p. 3727. 
Le Soron, Adams. Sen. p. 32, pl. 2, f. 3. 
Pileopsis antiquata, Forbes § Hanl. Br. Moll. vol. it. p. 462. 
Hipponyx antiquatus, Whe. in Zeit. f. Mal. 1853, p.79.—Proc. 
Zool. Soc. Jan, 1856, p. 3. 
Cochlolepas antiquatus, H. & A. Ad. Gren. i. 373. 
= Pileopsis mitrula, Lam. An. s. Vert. vol. vi. p. 610, no. 2. 
Capulus mitrula, Dunk. Ic. Moll. Guin. p. 36, no. 99. mee M., 
Cat. Cuba Moll. p. 32, no. 390. 
Hipponice mitrale, Defr. Journ. Phys. 1819, f. 4.— Blainv. 
Malac. pi. 50, f. 4. 
Hipponyx mitrula, Sow. Proc. Zool. Soc. 1835, p. 5 :—do. Thes. 
Conch. (inter Brachiopoda, ‘Nov. 1846) p. 369, no. 2, pl. 73, 
f. 18—20. 
Hipponyx Panamensis, C. B. Ad. Pan. Shells, p. 218, no. 328. 
Amalthea Panamensis, H. & A. Ad. Gen. i. 374. 
Known from H. serratus by the rounded base. Sowerby’s 
species was described, as of Zam. from Peruvian shells brought 
by Mr. Cuming. Prof. Adams, finding certain differences of 
form and markings between his Panama and Caribbean speci- 
mens, gave the Pacific shells afresh name. Both these and 
the Atlantic forms are however extremely variable in shape 
and details of sculpture. —QOnly three Mazatlan shells are 
referable to this species ; one, although only *062 long, has its 
apex decollated, is compressed and conical, with the beak 
much recurved, and has very fine, close, radiating stric, inter- 
rupted by lines of growth; the second, flattened and extremely 
_ worn, igs curiously indented in the region of the head; the 
