748 CLASS. XII. 
Tellinides Lam. Posterior margin of shell without irregular 
fold. 
Sp. Tellina Timorensis Buarnv., Tellinides Timoriensis LAM., Buatnv. Mala- 
col. Pl. 72, fig. 2. (DESHAYES has rejected this sub-genus, calling to mind 
that some Yelline by slow degrees conduct to this form. 
Fragilia Desu. Shell subtrigonal, gibbous, anteriorly rotun- 
date, posteriorly longer. Hinge with two teeth diverging in each . 
valve. 
Sp. Tellina fragilis L., Petricola ochroleuca Lam., Pout Test. utr. Sic. 1. Tab. 
xv. figs. 22, 24, Drsu. Conchyliol. Pl. 12, figs. 13—25. Hab. in Medi- 
terranean. 
Family XVIIL. Mactracea. Mantle open anteriorly, concrete 
posteriorly, produced into two trachez, in some separate, in others 
coalesced. Foot compressed, triangular. Shell equivalve, free. 
Ligament internal, received in a pit; in some an external ligament 
as well as an internal. Two muscular impressions remote. Im- 
pression of mantle marked posteriorly with a sinus, in some broad, 
in others deep, narrower. 
Amphidesma Lam. (in part), Rectuz, Dresu. Shell rotundate, 
suborbiculate, thin. Hinge with two teeth in each valve. Liga- 
ment double; external short; internal in a pit of hinge oblique, 
deep, narrow. 
Sp. Amphidesma variegata Lam., Encycl. méth., Vers. Pl. 291, fig. 3; Indian 
Ocean ;—Amph. solida Gray, DusH. Conchyliol. Pl. 11, figs. 1o—r12, 
South Sea, at the coast of Peru. 
Syndosmya Reciuz, Desu. Shell transverse, oval, thin, with 
anterior side shorter. Hinge with two teeth in right valve, with 
intermediate foveola receiving the single tooth of left valve. Two 
lateral teeth. Ligament double; external small, internal received 
in a spoon-shaped process. Animal with two trachee long, 
separate. 
Sp. Syndosmya alba, Amphidesma Boysii LAM., Diese. Conchyl. Pl. 8 bis, 
figs. 6—8, &e. 
Trigonella DA Costa, Des. (Species of Mactra GMEL., sub- 
genus of Mactra Cuv., spec. of Lutrarta Lam.) Shell orbiculato- 
trigonal, flat, subequilateral, with anterior side shorter, rotundate, 
posterior subhiant. Hinge narrow, with two small teeth in right 
