NATURAL HISTORY. xcv 



three-fourths of the second pair, and along about half of the tliiid and fourth pairs of 

 arms, beyond which the suckers are aggregated into irregular transverse rows of from 

 three to five, diminishing in size to the apex of the arm. In this respect there is an inter- 

 mediate structure between Sepiola, in which the suckers arc in a double alternate 

 scries along the whole arm; and Sepia, in which they are aggregated from the com- 

 mencement. The horny cup in each acetabulum has its margins entire : and its 

 diameter is equal to one-third of the fleshy sphere in which it is implanted. 



The tentacles or proboscides * are round, and slightly dilated at their extremities, 

 which are beset for about nine lines by minute and close-set suckers ; these diminisli 

 in size towards the extremity of the tentacle, and the largest of them do not exceed 

 one-fiftieth of an inch in diameter. The horny cup of these acetabula is propor- 

 tionately larger than in those of the brachia, and their pedicles are longer. (See b, 

 pi. C.) A narrow membranous expansion is extended along the sides of the dilated 

 extremities of the tentacle. 



The tentacula emerge from within the membrane extended between the third and 

 fourth pairs of brachia, but this interbrachial fold, though of greater breadth, does not 

 connect the arms together for a greater extent than the membrane between the third 

 and second, or that between the second and first pairs of legs; but there is no coiTe- 

 sponding fold between the ventral pair of amis. In this respect Rossia resembles 

 Sepiola and Sepia; in all of which, therefore, the interbrachial membranes have 

 obviously other uses than to protect the tentacles, which can be retracted into a cavity 

 below the base of the arms ; they probably serve, but in a minor degree than in 

 Octopus, as a retropulsive fin. 



The eyes of the specimen were of large size, forming the usual convexity on eacli 

 side of the head ; they were, however, as has been before mentioned, almost com- 

 pletely hidden from view by the contraction of the lower eyelid principally, the open- 

 ing of the fold corresponding to the transparent portion of the integument continued 

 over the eyeball (for the animal cannot be said to possess a true cornea), was of a 

 longitudinal figure, and dorsal in its position. In Sepiola there is a slight fold beneath 

 the eye, corresponding to the largely developed eyelid in Russia, but there is a greater 

 proportionate breadth of the head at this part in Sepiola. 



The siphon or funnel extends to within a line of the interbrachial membrane of the 

 ventral pair of arms, resembhng in this respect Sepiola rather than Sepia, or Sepw- 

 teufhis, where the funnel reaches only half-way between that part and the margin of 



• Tins superadded pair of elongated avrns were termed by Aristotle Trpo^aKilai, in contradistinction lo 

 the ordinary eight arnns, wWclihe calls voSeg. — hist. Anima!.,hh. iv., c. 1. 



