6 HOYLE, Genera of Recent Dibranchiate Cephalopoda. 



(A narrow fin extending round the body Hoy lea. 



No fin 15 



14 



15- 



16. 



17- 



'Body firm ; arms comparatively long, usually at least 



twice the length of the body Moschites. 



Body gelatinous, semitransparent ; arms shorter than 



the body, except the third pair in some cases 16 



'A median septum present in the mantle csivity... Eledonella.^ 



'No median septum in the mantle cavity .Japetella.^ 



'A broad fin on either side of the body, rendering the 

 outline heart-shaped Pmnoctopus 



INo lateral fins 18 



/An aquiferous pore leading into a pouch between each 



; pair of arms Cistopus 



vNo aquiferous pouches 19 



(The third arm of the right side hectocotylised Polypus J 



(The third arm of the left side hectocotylised Scaeurgus.'' 



/A spiral internal shell, protruding on the dorsal and 



) ventral surfaces. (Spirulid^) Sptrula.^ 



vNo spiral shell 21 



fEye covered by a continuous membranous lid. 

 21J (MYOPSIDA) 22 



-Eye with a perforated lid. (CEGOPSIDA) 39 



Body short rounded, with separate ovate lateral or 

 subterminal fins 23, 



19 



22. K 



Body oval or elongate, with fins either marginal or 

 terminal 34 



