448 Mr. E. S. Russell on the Cephalopoda 



pair, where it is less developed. The suckers are in two rows 

 slightly alternating, and are perfectly formed, though small, 

 at the extreme tips of tiie arms. Near the mouth tiiree or 

 four suckers stand in a single row. There are about 60-70 

 suckers on each arm of the large female, and the lai'gest of 

 them measures 4 mm. in diameter. 



The hectocotylisation closely resembles that of P. arcticus^ 

 but it is, relatively to the length of the arm, very much 

 smaller. Thus it measures 14 mm. in length on an arm 

 measuring 11'4 cm. The calamus brachialis is small and 

 triangular, the ligula copulatoria is broadly oval and comes 

 to a blunt point. There are 11-13 ridges on the ligula. The 

 hectocotylised arm is little shortened ; the web is developed 

 especially on the ventral side ; there is a sperm-canal (21 ram. 

 long) running down the ventral edge of the web to midway 

 between the third and fourth arms. 



I give below the dimensions of a large female and of a 

 male : — 



Dimensions {in cm.). 



Length of mantle, dorsally, to eyes 4*8 4'2 



Breadth of mantle 40 3-6 



„ head, dorsally, across eyes 3'0 2'5 



Depth of body 37 3-0 



„ head 22 1-8 



Length of first arm, from beak 17-0 13-2 



„ second arm, from beak 160 12-6 



„ third (non-hectocotylised) loO 12-5 



„ „ (hectocotylised) 11 "4 



„ fourth arm 140 ll'O 



„ -sveb between first pair of arms .... 4'2 3'8 



,, „ fourth pair of arms . . 3'0 3"3 



Number of suckers on first (right) arm 73 67 



'J'he hectocotylised arm of the male measures 11 4 cm. in 

 length, of which 10 cm. bear suckers (to the number of 40). 

 The hectocotylised part is 1'4 cm. long and 9 ram. broad. 

 The ligula bears 13 transverse ridges. 



Poll/pus faeroensis is fairly closely allied to P. arcticus 

 (Prosch), but it differs in certain well-defined ways. The 

 body is not so broad, and the distinction between head and 

 body is very much better marked. The arms are longer in 

 proportion to the body. The hectocotylised arm is much 

 longer and tlie hectocotylised part much shorter than in 

 P. ai'cticus [Octopus bairdii of Verrill), in which the hecto- 

 cotylised part is one-third the length of the arm. Finally, 

 the papulation is distinctive. 



