36 JURASSIC RHYNCHONELLIDS 
The suberect beak is narrow and characteristically pronounced. The interarea 
and beak ridges are scarcely developed. The submesothyridid pedicle opening is 
small and flanked by conjunct deltidial plates. 
DIMENSIONS OF FIGURED SPECIMENS. 
length thickness width 
2°62 cm I-40 cm 2°50 cm 
2°76 cm I-97 cm 2:94 cm 
Internal characters. Pedicle valve. The shell is massive ; lateral cavities are not 
developed as the dental lamellae do not appear to touch the ventral shell wall. A 
pedicle collar is present. The teeth are strongly developed and lateral denticulae 
are present. 
Brachial valve. The falcifer crura are exceptionally wide distally. Inner and 
outer socket ridges are very strongly developed. 
Fic. 15. Transverse serial sections of Lacunosella cracoviensis (Quenstedt). ‘‘ Malm beta/ 
gamma’’. Wiirgau, Germany. (4). 
