406 MOLLUSCA SUB-KINGDOM VI 
anterior (A) is longer and thinner than the others, which are thickened at the internal 
end and carry a small tubercle above. In the two sub-genera, d’Orbignyia, Woodward 

Fic. 736. 
Hippurites radiosus, Desm. Upper Cretaceous (Dordonian); Royan, Charente. «a, Upper valve (A, Sinus of 
the hinge ; B, C, Grooves corresponding to anterior and posterior columns of the lower valve; c, Anterior, and 
c, e’, Posterior processes of the clithrum). 6, Interior of lower valve seen from above (A, Sinus; B, C, Posi- 
tion of anterior and posterior columns; a, a’, Adductor scars; d, Socket of anterior, and d’, d’, of posterior 
processes of clithrum ; 7, Body chamber of shell; x, Vacant cavity near the sinus). 2/3 (after Bayle). 
(H. biloculus, Lam.), and Batolites, Montfort (H. organisans, Lap.), the anterior sinus 
disappears entirely. In Pironaia, Menegh., a number of accessory folds appear behind 
the two columns. According to Douvillé, the two posterior 
columns are homologous with the smooth bands of Radio- 
lites, and indicate the position of the siphons. Woodward 
supposes that the pit («) contained the internal ligament ; 
but so far, remains of the ligament have only been found 
in the bottom of the outer anterior sulcus, where it seemed 
to form a vertical band. The second adductor scar is 
small, and located between the sulcus and the anterior 
column (B). The clithrum of the upper valve is extremely 
difficult to prepare, and is known in only a few species. 
The anterior process shows near its base two tubercles 
1% (a, w), which correspond to the divided adductor scar of 
Fic. 737. the lower valve. Behind the anterior there are two supple- 
Hippurites cornu-vaceinum, Golat, Mental processes, which are received into the sockets d’ and 
Pp en nea LeOnES aed amid d” of the lower valve. The species are very abundant in 
valves showing the interlocking the Middle and Upper Cretaceous, and occur chiefly in 
eae relation of the shell- i¢toral shallow water deposits. The most noted localities 
: are the Alps and Pyrenees, Provence, Charente, Istria, 
Dalmatia, Greece, Sicily, Asia Minor, Persia, and Algiers. 
Barrettia, Woodward. Cretaceous; Jamaica and Guatemala. 

Superfamily 7. LUCINACEA. Anton (emend.) 
Shell with the anterior adductor scar narrower, produced ventrally ; posterior scar 
>] Y; 
shorter, rounded ; pallial line simple ; foot elongate, sub-clavate ; hinge feeble, teeth radial; 
often obsolete. 
