132 SOLENID^. 



Shell subcylindrical, transversely elongated, rounded and 

 gaping at the extremities ; beaks anterior to the centre ; ante- 

 rior muscular impression elongated, subtrigonal ; pallial impres- 

 sion with a small sinus. 



Siphons shortly produced and separate ; foot large, abruptly 

 truncate. Iijhabits the muddy estuaries of rivers. 



Ceeatisolen, Forbes. 



Syn. — Pharus, Leach, teste Gray, 1840. Polia, d'Orbigny. 

 Solecurtoides, Desm, 



Distr.' — 2 sp. Britain, Mediterranean, Senegal, Red Sea, 

 Singapore. Fossil, 3 sp. Miocene ; Italy. G. legumen, Linn, 

 (cvi, 12). 



Shell narrow, subequilateral, anterior adductor impressions 

 elongated, a second pedal scar near the pallial sinus. 



Animal with a long, truncated foot ; siphons separate, diver- 

 ging, fringed. 



Legumenaia, Conrad, 1858. 



Distr. — L. elliptica, Conr. (cvi, 14). Cret. ; IT. S. 



Yalves very inequilateral ; hinge with two very slender teeth 

 in the right valve under the beak, and one posterior, very 

 oblique, prominent, lamelliform tooth. This group was proposed 

 for a cretaceous species ; the form of the teeth and their posi- 

 tion agrees with Novaculina, but the posterior tooth is not lamel- 

 liform in this genus. A character of further importance is 

 stated to be the shortness of the posterior part of the shell, 

 which is not seen in any of the European or Indian cretaceous 

 species ; it does, however, occur in some of the recent American 

 species of Tagelus, from which Legumenaia would differ by its 

 dentition, but externally it would seem impossible to distinguish 

 between both of them. 



Leptosolen, Conrad, 1861. 



Distr. — L. bipKcata, Conr. Cretaceous ; IT. S. 



Elongated, thin in substance, straight, with the dorsal and 

 ventral margins parallel; plicated anteriorly, open at both ends; 

 beaks not nearly terminal ; hinge of the right valve with one 

 direct tooth, convex anteriorly, truncated behind ; an internal, 

 rounded, direct rib commences under the cardinal margin, grad- 

 ually becomes less prominent, and disappears towards the 

 ventral margin. 



If the existence of a single tooth in the right valve can be 

 considered as a permanent, distinctive character, the separation 

 from Siliqua would have good grounds. The tooth is said to 

 be broadest at the hinge-plate, and tapers to a very acute edge, 

 which is expanded in the direction of the shell's diameter. This 

 peculiarity in the form of the principal or cardinal tooth is often 



