268 TESTACEOUS MOLLUSCA. 
margin of the anterior hiatus formed by an internal rib ; auricles 
small, anterior acute, posterior obtuse ; hinge area narrow. 1,50.. 
0,80. Tahitiand Philippines. 
L. Arcuara. Sow. Th. p. 86.t. 22. f. 41, 2. Closely resembling 
the last but more gaping, and having the ventral margin expanded 
and slightly angular. 14...-.°, Panama, ec. 
L. Aperta* Sow. Th. p. 87. t. 22. f. 26,7, 8, 9.—L. Trenzra. 
Turt. Zool. J. 2. p. 362. t. 18. f. 2.—Phil. p. 77.—L. Burwata. 
Payr. Corsic. p. 70. Thin, rather flat, obliquely oval or elongated, 
smooth at the sides, minutely striated in the middle: posteriorly 
slightly, anteriorly widely, gaping, the anterior hiatus margined by 
a strong internal rib; anterior auricles acute: hinge area small. 
4% .-3 Britain.) 
L. Dentata Sow. Th. p. 87. t. 22. f. 30,1. Obliquely elongated, 
thin, rather compressed, the posterior side slightly, the anterior ra- 
ther more widely gaping; a slight internal rib, forms the margin of 
the anterior hiatus; anterior auricles extremely sharp, with a 
notch underneath them; hinge area deep; ribs eighteen, distant, 
granulated, their terminations producing a dentated ventral margin. 
OAM 
ge 3 
L. Cumincn Sow. Th. p. 87. t. 22, f. 24, 5. Thin, small, 
obliquely elongated, rather inflated, nearly five-sided, almost closed 
at the margins; anteriorly very slightly gaping, ventral edge sub- 
quadrate; hinge short; auricles short and rather obtuse; anterior 
margin obtusely angulated ; ribs twelve, central, nearly obsolete, 
toothed at the margin. 0,40..0,25. Isle of Luzon, Philippines. 
PECTEN. 
Free, regular, inequivalve eared ; the dorsal edge transverse, straight; 
beaks contiguous: hinge without teeth ; lhgament internal, placed 
in a triangular cavity. 
P. Maximus* Lam. 1.—Sow. Th. f. 98 to 100.—Turt. B. p. 207 
—Mont. p. 143.—E. t. 209. f. 1.—Ostrea M. Lin. 1144.—D. 
p. 247.—Knorr. 2. t. 14. f. 1—W. t. 11. f. 1. Suborbicular, 
rather spread at the sides, rather depressed; umbones smooth, 
margins striated; upper valve concave near the umbo, slightly 
elevated near the middle ; auricles large, rectangular, striated : hinge 

1 Probably the Ostrea Hians of Gmelin, a species wholly derived 
from the figure in Schroeter’s Einlungen ¢. 9. f. 4. (D. p. 270.—W. 
t. 11. f.53.—L. Lincuaruta var? Lam.) is an aged specimen of 
this species. 
