404 MOLLUSCA SUB-KINGDOM VI 
two vertically projecting striated processes (Fig. 729, ¢, c’), fitting into sockets near 

a, b, Radiolites (Biradiolites) cornu-pastoris, d’Orb. Middle Cre- 
taceous (Carentonian); Pyles, near Périgeux. a, Shell with closed 
valves. , C, The two more finely ribbed vertical bands. 6, Interior 
A , A Fic. 730. 
of larger valve, viewed from above. a, a’, Adductor scars; m, Pallial 730 
line ; uw, Space occupied by soft parts; 7, Empty space between the Sphaerulites angeiodes, Lam. Upper 
sockets. 1I/y (after Bayle). c, Opercular valve of R. Bowrnoni, Desm. Cretaceous ; Gosau, Austria. a, Shell 
sp. Upper Cretaceous (Dordonian); St. Mametz, Dordogne. a, Au- with closed valves, 1/j. 6, Opercular 
terior ; a’, Posterior myophore; ¢c, c’, Anterior and posterior processes valve, 1/;. A, Sinus of hinge. a, a, 
of clithrum. 1/3 (after Bayle). Myophores; ¢,c’, Processes of clithrum. 
the outer wall of the fixed valve; next to and outside of the sockets are two large 
unequal slightly excavated adductor scars, 
corresponding to two broad myophores in the 
upper valve. Middle and Upper Cretaceous ; 
Europe and Texas. 
Sub-genera: Lapeirousia, Bayle. The smooth 
bands correspond internally to two prominent 
tubercles. Synodontites, Pirona. Has the two 
teeth of the upper valve fused. 
Sphaerulites, 
Delam. (Radiolites, 
Birostrites, Lam. ; 
Jodamia, Defr. ; 
Dipilidia, ? Agria, 
Math.), (Figs. 730- 
732). Externally 
like Radiolites, ut 
5 : Fic. 731 Sphaerulites foliaceus, Lam. Carentonian; [le 
without the two ae fhe d’Aix, Charente. A, Sinus of the hinge. a, a’, 
es valves wi Portion of the outer shell layer Anterior and posterior adductor sears ; d, d’, An- 
bands ; valves ha ith of the lower valve of a Sphaeru- terior and posterior grooved sockets for the pro- 
a re-entrant sinus lites or Radiolites showing the cesses of the upper valve; #, 2’, Empty spaces of 
ie rs large hollow prisms. Cretace- the ligament pits; y, Cavity at the inner end of 
between the tec th, ous; Monte Gargano, Italy. 1/. the sinus. 2/s (after Goldfuss). 
which fit into sepa- 
rate pits (d, d’), usually joined by a ridge with the inner margin of the sinus; the two 

Fig. 782. 
