404 MOLLUSCA SUB-KINGDOM vi 



two vertically projecting striated processes (Fig. 729, c, c'), fitting into sockets near 



a, b, Radiolites (Biradiolites) cornu-pastoris, d'Orb. Middle Cre- 

 taceous (Carentonian); Pyles, near Perigeux. a, Shell with closed 

 valves. B, C, The two more finely ribbed vertical bands, b, Interior 

 of larger valve, viewed from above, a, a', Adductor scars ; m, Pallial 

 line ; u, Space occupied by soft parts ; x, Empty space between the 

 sockets. 1/2 (after Bayle). c, Opercular valve of R. Bournonl, Desm. 

 sp. Upper Cretaceous (Dordonian) ; St. Mainetz, Dordogne. a, An- 

 terior ; a', Posterior myophore ; c, tf, Anterior and posterior processes 

 of clithrum. 1/3 (after Bayle). 



FIG. 730. 



Sphaerulites angeiodes, Lam. Upper 

 Cretaceous ; Gosau, Austria, a, Shell 

 with closed valves, i/j. b, Opercular 

 valve, i/i- A, Sinus of hinge, a, a', 

 Myophores ; c, 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, but 

 without the two 



FIG. 



banrh val VP? witli Portion of the outer shell layer 

 bands , A aives witn of the lower valye of & Spht J> ru _ 



a re-entrant sinus lites or Radiolites showing the 

 s hollow prisms. Cretace- 

 Monte Gargano, Italy. i/ x . 



Sphaernlitcs foliaceus, Lam. Carentonian ; He 

 d'Aix, Charente. A, Sinus of the hinge, a, a', 

 Anterior and posterior adductor scars ; d, d', An- 

 terior and posterior grooved sockets for the pro- 

 cesses of the upper valve ; x, x', Empty spaces of 

 the ligament pits ; y, Cavity at the inner. end of 

 the sinus. 2/ 3 (after Goldfuss). 



between the teeth, 

 which fit into sepa- 

 rate pits (d, d'\ usually joined by a ridge with the inner margin of the sinus ; the two 



