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Bulletin 35 



Page 173 



form and its regular equal concentric riblets, which are not 

 (at least posteriorly) parallel with the lower margin. 



9. Leda illecta, Guppy (PI. vii., f. 5). 



Leda illecta, Guppy, Proc. Scient. Assoc. Trinidad, 1867, 

 p. 174. 



A Leda somewhat likeZ. eburnea$ow., distinguished from 

 the preceding by its smoothness and somewhat pear-shaped 

 form. I copy 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, scarcely 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 (PL vii., f. 7). 

 Leda bisculcata, Guppy, Geol. Mag. 1867, p. 500, f. 2. 



This is as tumid as L. acuta, 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. jamaicensis, whose ornamentation, however, 

 is of a much bolder character. 



Miocene, Jamaica. 



11. Leda jamaicensis, Orb.. 



Leda jamaicensis, D'Orbigny, Moll. Cuba, vol. ii., p. 263, 

 pi. xxiv., f. 30—32. 



This has not been recorded as fossil. Examples dredged 

 in the Gulf of Paria differ slightly from D'Orbigny 's figure. 



