68 MAZATLAN BIVALVES 
the inner one turned backward. In the adult, this row ceases. 
The very young shell has none; while in D. Veneris they ap- 
pear much earlier. The spines in the large row are generally 
rather straight and very long; one measured long. 1°88, and 
others must have been longer when perfect. The concentric 
ridges are not always parallel with the margin of the shell, and 
often bifurcate very irregularly. I have examined carefully 
nearly 4,000 specimens, almost all of which had fallen victims 
to the voracious appetites of gasteropods, who drill their holes . 
generally near the apex. Epidermis extremely thin: spines 
channeled. The spine of the smallest well marked specimen 
measures “41; the shellitself long. °49, Jlat.°59, alt. ‘31. 
The largest (without spines) Wh. PE DOs ees eh de oes oe 
The most transverse 53). bare. eo ty 4, dese 
Hab.—Salango, in sandy mud, 9 fm. ; Tumbez (Peru) soft mud, 
5fm.: Cuming—San Blas (Culf of California), sandy mud, 
7 fm., Col. Cuming.—Payta, (Peru,) D’ Orbigny.— Mazatlan ; 
Col. Jewett, (Gould ms.)—Do; extremely abundant, L’pool 
&§ Havre Coll. 
Tablet 294 contains 2 minute valves, (the smallest ‘025 
across,) which probably belong to this species, though they 
shew no trace of spines. 
Tablet 295 contains 9 very young specimens, rounder form, 
with rather coarser striz.—296, 6 do. rather older.—297, 3 do. 
adolescent.—298, 2 do. very large.—299, 9 very young, trans- 
verse form.—300, 8 do. rather older.—301, 6 do. adolescent.— 
302, 3 do. adult.—303, 5 young, pale var.—304, 3 do. adult.—305, 
4 sp. with extra spines.—306, 1 large do. shewing epidermis.— 
307, 3 young, spines forming at margin.—308, 3 do. spines 
strangely curved.—309, 2 do. small spine growing by and in 
broken large one.—310, 1 adult, with spurs on bottom of 
spines.—311, 1 do. two spines growing together.—312, 1 do. 
very crowded spines at margin. In all, 72 specimens. 
96. Dione ? vuLNERATA, Brod. 
Cytherea vulnerata, Proc. Zool. Soc. 1835, p. 46.—Hanl. Deser. 
Cat. p. 105.—Catlow. Cat. p. 40, no. 116.—Sow. Thes. Conch. 
p. 632, pl. 131, f. 95, 96. 
Dione vulnerata, Desh. B. M. Cat. Ven. p. 60, no. 15. 
Tablet 313 contains 2 minute opposite valves which may 
belong to this species. 
Hab.—Real Llejos, in sandy mud, 6 fm. Cuming.—? Mazatlan ; 
2 valves off Spondylus ; L’pool Col. 
