MAZATLAN BIVALVES >; 
Shell closely resembling T. purpurea; from Real Llejos, 
Cuming. It differs from the plate in Beech. Voy. in having 
the umbos less pointed and the teeth smaller. The surface 1s 
crowded with extremely close concentric strie, decussated 
(except on the fold area) by very fine radiating lines, which 
beeome obsolete, in one valve only, on the ventral portion. 
The fold area is nearly smooth (except lines of growth) on one 
valve ; on the other, with rather sharp raised ridges, carrying 
on generally every other one of the concentric strie. EHpiden 
mis light brown, very thin, coarser on the fold area. The 
species mucb resembles (though smaller) T. princeps, a valve 
of which was sent from 8. W. Mexico, (P. PC.) It gapes on 
each side, and might almost pass for a Sanguinolaria, but for 
its flatness. Long. 1°18, lat. 2°12, alf. °31. 
Hab.—Mazatlan, 3 specimens (Mus. Archer, Darbishire, B. M.) 
L’pool Col. 
Tablet 110 contains one specimen. 
AQ. Tertina PP MazarLantica, Desh. 
YT. Mazatlandica, Proce. Zool. Soc. 1854, p. 359. 
Tablet 111 contains a minute fragment which may be the 
young of this species, though the characters of the hinge are 
somewhat different. The Cumingian type measures long. ‘79, 
lat. Ii3s all. 32: 
Hab,—Mazatlan : Col. Cuming.—?? Do. in Spondylus washings, 
Ly pool Col. 
50. Tenutina Dompet, Hanl. 
Proc. Zool. Soc. 184A, p. 144.—Hanl. in Sow. Thes. Conch. 
p. 323.—C. B. Ad. Pan. Shells, p. 282, no. 464. 
A plain, white, oblong shell, much swollen and produced 
anteriorly. Zong. 1°1, lat. 1°45, alt. °5. 
Hab—Panama, in sandy mud, 12 fm. Cwmzng.— Panama, rare. 
C. B. Ad.—Mazatlan, 2 specimens, L’ pool Col. 
Tablet 112 contains one specimen. 
