THE CEPHALOPODA 



FlG, 39. AsTEROCERAS OBTUSUM, J. SOWERBY, SlNEMURIAN 

 (LOWER LIAS), LYME REGIS. 



a, Side view; 6 t apertural view (Xj.), (Original); c, suture-line (after 

 d'Orbigny. The arrow denotes the middle line of the periphery and 

 points towards the body-chamber ; the horizontal line is the guide-line, 

 EL, External lobe ; ES, external saddle; LLi, LL2, first and second 

 lateral lobes; LSi, LSz, first and second lateral saddles; AL, AS, 

 auxiliary lobe and saddle. 



