N 
N 
JURASSIC RHYNCHONELLIDS 
DIMENSIONS OF FIGURED SPECIMENS. 
length thickness width 
0-80 cm 0:55 cm 0-75 cm 
0-92 cm 0-67 cm 0-83 cm 
0-88 cm 0:60 cm 0:86 cm 
Internal characters. Pedicle valve. The dental lamellae are very much reduced 
and not attached to the ventral wall of the shell. The teeth are inserted at a 
relatively shallow angle, as seen in transverse section. 
Brachial valve. There is no median septum. The sockets are shallow and inner 
and outer socket ridges are scarcely differentiated. 
OQ OO 
1:0 0-9 O77 
| | 9 (4) 
€ s 2 ih | . 
144 1:3 
Fic. 9. Transverse serial sections of Monticlarella striocincta (Quenstedt). ‘‘ Weiss Jura 
alpha ’’. Lochengriindle, Germany. Specimen donated by the University of Tiibingen. 
(x8). 
DisTRIBUTION. The Swabian and Franconian Jura, Poland and the southern 
French Jura are the only areas from which the species has been definitely recorded. 
It is considered likely that M. striocincta could occur quite widely in the French Jura 
but has been overlooked on account of its small size. 
