104 CLASSIFICATION. 



Fischer (see ante^ p. 55), that many of these genera were really 

 dibranehiate, and should be ranged with Spirula rather than 

 with Nautilus. I shall imitate the reserve of the latter gentle- 

 man, by making no change in the classification of these fossil 

 forms 



Family I. OCTOPODID.i:. 



Synopsis of Genera. 



a. Arms with two rows of suckers. 



* Body not finned. 



Octopus. Body rounded. Arms long. Suckers sessile. Third rijiht arm 



of male hectocotylized. 

 C'iSTOPUS. Difters from Octopus in having a small aquiferous system, 



consisting of a bag with a small pore at its lower edge, upon the weh 



between each arm. 

 SCiEURGUS. Hody oval ; wider than the head ; arms short ; cups with 



narrowed bases. Third left arm hectocotylized. 



* * Body finned. 



PiNNOCTOPUS. 



b. Arms with a single row of suckers. 



* Not finned. 



Eledone. Body rounded, without fins. Third right arm hectocotylized. 



Bolit^:na. More gelatinous than Eledone ; suckers smaller, less 



developed. 



* * Finned. 



CiRROTEUTHis. Body with two transverse medial fins ; mantle united 

 to tlic head nearly all round, by a cervical band; arms united by a 

 web nearly to their tii)s. 



Family II. TilEMOCTOPID.E. 



Tremoctopus. Body rounded, head lai-ge, band of the neck very small. 

 Funnel short. Two acjuifei-ous pores in the neck. Third right arm hec- 

 tocotylized, fringed on the sides, and developed in a sack-like aper- 

 ture on the side of the head. 



Parasira. Body rounded ; head small and short ; neck-band rather 

 broad. Funnel long. No water pores in the neck, two at the base of 

 the siphon. Third right arm hectocotylized, not fringed, developed from 

 a pedicelled sack. Male very different from the larger female. 



Haliphron. Arm only known. With bell-shaped cups, having lily- 

 like borders. 



