388 



DECAPODA 



CHAP. 



As a rule the rostrum is the only portion which has been 

 preserved. 



Fam. 3. Belosepiidae. — Phragmocone short, slightly curved, 

 chambers small, placed at the posterior end of a sepion, rostrum 

 solid, obtuse. — Eocene (Paris, Bracklesham, etc.). 



Fam. 4. Belopteridae. — Sepion not known; phragmocone 

 curved, siphuncle on the ventral margin, rostrum well developed, 

 pointed. Principal genus, Spirulirostra. — Miocene of Turin. 



These two families, with their small, curved 

 phragmocone and (in the case of the Belose- 

 piidae) large sepion, are clearly intermediate 

 between the Phragmophora and Sepiophora. 



Fig. 247. — Shell of Spirilla Peronii Lam. A, Outside view ; B, 

 showing last chamber and position of siphuncle ; C, in sec- 

 tion, showing the septa and course of siphuncle ; D, shell 

 broken to show the convexity of the inner side of the septa ; 

 E, portion of a septal neck. 



FiG.248.— Spirw/a Per- 

 onii Lam. : d, ter- 

 minal sucker ; /, 

 funnel; s^, a^, pro- 

 jecting portions of 

 shell, the internal 

 part of which is 

 dotted in. (From 

 Owen and A. Adams 

 combined.) 



Some authorities place them with the latter group. 



B. Sepiophora. — Shell internal, consisting usually of (a) 

 an anterior cancellated portion, (h~) a posterior laminated por- 

 tion, the laminae enclosing air. It terminates in a very 

 rudimentary phragmocone and a rostrum, but there is no 

 siphuncle. 



Fam. Sepiidae. — Eyes with cornea complete, body oval, fins 

 narrow, lateral, as long as the body, generally united behind ; 

 sessile arms short, tentacular arms long, acetabula generally in 



