130 



THE VOYAGE OF H.M.S. CHALLENGEE. 



with coarse rugosities disposed in curved lines parallel to the anterior margin ; a distinct 

 but low rib runs down the centre. The ventral surface is elevated on either side of 

 a deep median groove; the last loculus has an index of 22 in the male and 17 in the 

 female specimen, and is bounded posteriorly by two slightly wavy lines, meeting at an 

 acute angle; t}iQ striated area is long, and the angle between the striae widens posteriorly. 

 The imier cone is very well developed ; the limhs arise one-fifth the length of the shell 

 from the posterior end, and gradually become more elevated until they enclose a deep 

 conical cavity. The spine is strong and pointed (PL XVIII. figs. 1, 2), somewhat curved 

 laterally in the female example. 



Dimensions^ 



Length, total, 



End of body to mantle-margin, dorsally. 



End of body to mantle-margin, ventrally, 



End of body to eye,. 



Breadth of body, . 



Breadth of head, . 



Eye to edge of umbrella, . 



Breadth of fin, 



Diameter of largest sucker on sessile arm, 



Length of shell, . 



Breadth of shell, . 



Length of first arm, 

 Length of second arm. 

 Length of third arm. 

 Length of fourth arm. 



240 mm. 



160 „ 



UO „ 



155 „ 



75 „ 



55 „ 



40 „ 



20 „ 



2-5 „ 



163 „ 



52 „ 



Eight. 

 65 mm. 

 65 „ 

 63 „ 

 70 „ 



Left. 

 68 mm. 

 60 „ 

 58 „ 

 63 „ 



This fine species approaches Sepia aculeata, van Hasselt, but lacks the suckers on 

 the buccal membrane,^ and also the callosity of the inner cone at the posterior extremity 

 of the shell. This cannot be due to immaturity, for the two specimens in the Challenger 

 collection are larger than undoubted specimens of Sepia aculeata, in which this 

 peculiarity is well marked. 



It has moreover some resemblance to Sepia brevimana, Steenstrup, but the shell is 

 not so broad in proportion nor so regularly elliptical, being rather more dilated in its 

 posterior half. 



Perhaps, however, its closest relationship is with an unpublished form in the 

 Copenhagen Museum, labelled " Sepi^ rostrate affinis," but that the posterior extremity 

 of its shell is more rounded (both being females). The thickened spermatic pad is 

 more fully developed in the Challenger than in the Copenhagen specimen, which may, 



1 The dimensions above are from the male specimen ; in the female the length of the body is 143 mm. dorsally and 

 123 mm. ventrally and the breadth 70 mm., length of shell 143 mm., breadth 54 mm. 



2 Steenstrup, Hemisepius, pi. ii. fig. 4. 



