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form and its regular equal concentric riblets, which are not 
(at least posteriorly) parallel with the lower margin. 
9. Leda illecta, Guppy (PI. \’ii. , f. 5). 
Leda illecta, Gupp}^ Proc. Scient. Assoc. Trinidad, 1867, 
p. 174. 
A Leda somewhat likeZ. eburneaSov; . , distinguished from 
the preceding by its smoothness and somewhat pear-shaped 
form. I cop5" the original description; “Smooth, ovate- 
transverse, inequilateral, somewhat tumid on the central 
portion, posterior end produced into a rostrum which is 
almost curved upwards ; hinge-line .somewhat deflected 
upwards, and interrupted at the umbo ; umbones approxi- 
mated, scarce!}- prominent beyond the hinge-line ; posterior 
cardinal area broad, .smooth, and ill defined.’’ Length 10 mill., 
height 6 mill. 
Eocene, Manzanilla, Trinidad. 
10. Leda bisulcata, Guppy (PI. vii., f. 7). 
Leda bisculcata. Guppy, Geol. Mag. 1867, p. 500, f. 2. 
This is as tumid as L. aaita, Gabb, but is more rostrated, 
the riblets are much finer, and are parallel with the margin, 
whilst the sulcus down the anterior end forms a good dis- 
tinguishing mark. A trace of a similar sulcus may be 
observed in L. jamaice^isis, whose ornamentation, however, 
is of a much bolder character. 
Miocene, Jamaica. 
II. Leda jam aice 7 isis. Orb. 
Leda jamaicensis, D’Orbigny, Moll. Cuba, vol. ii., p. 263, 
pi. xxiv., f. 30—32. 
This has not been recorded as fos.sil. Examples dredged 
in the Gulf of Paria differ slightly from D’Orbigny’s figure. 
