CLASS I 



PELECYPODA 



483 



with tlie smooth band« of Radiolites, and indieate the position of the siphons. 

 Woodward supposes that tlie pit (x) contaiiied the internal ligarnent ; but so far, 





'ö\nilUi:|| 



Hippurites gosaviensis 

 Douv. Upper Cretace- 

 ous ; Gosau Valley, 

 Austria. 1/2- 



Fio. 783. 



Hipjmrites oppeli Douville. Nefgraben, near Russ- 

 bach, Salzburg. A, B, C, Iinpressed lines bounding 

 convex vertical areas (columns) corresponding to the 

 region of the hinge. 1/2. 



Fig. 784. 



Hippurites organisans 

 Montf. Vertical section 

 of a valve below the 

 living Chamber, show- 

 ing the septa and inter- 

 septal cavities of the 



middle layer. 



Vi. 



remains of the ligainent have only been found in the bottom of the outer anterior 

 sulciis, where it seemed to form a vertical band. The second adductor scar is small, 

 and located between the sulciis and the anterior column (B). The clithruni of the 



Hippurites radiosus Desm. Upper Cretaceous (Dordonian) ; Royan, Charente. a, Upper valve (^1, Sinus of 

 the hinge • B C Grooves corresponding to anterior and posterior coluinns of the lower valve ; c, Anterior, and 

 c' c" Posterior processes of the clithrum). h, Interior of lower valve seen from above (^1, 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 ; u, Body Chamber of shell ; x, Vacant cavity near the sinus). 2/3 (after Bayle). 



Upper valve is extremely difficult to prepare, and is known in only a few species. 

 The anterior process shows near its base two tubercles (a, «')> wliich correspond to 



