REPORT ON THE CEPHALOPODA. 157 



body, for wliile in the youngest stage examined the fin is much shorter than the anterior 

 cylindrical portion of the body, in the oldest it is considerably longer. This has a very 

 important bearing on the use of the proportionate length of the fin as a specific character ; 

 Lafont 1 has given a table of the Loligos of the French coast in which they are sub- 

 divided according as the fins are greater or less than half the length of the body. A 

 consideration of the development shows, however, that species are not comparable in 

 this respect unless they have attained the same stage of growth. 



Loligojaponica, Steenstrup, MS. (PI. XXIV. figs. 7-15). 



... Loligo japonica, Steenstrup, MS. in Mus. Havn. 

 1885. „ „ Hoyle, Diagnoses 11., p. 187. 



1885. „ „ Hoyle, PreUm Rep. II., p. 290. 



Habitat. — Yokohama, Japan. Purchased in the market. One specimen, $ . 



TJie Body is only moderately elongated, being about three times as long as broad, 

 and bluntly pointed behind. The Jin is a little more than half the length of the body, 

 about as long as broad, rhomboidal, rounded laterally, and very slightly notched at the 

 anterior angles. The mantle-margin curves gradually forward to a projecting point in 

 the dorsal median line, and is deeply emarginate ventrally. The siphon is short and of 

 the usual form. 



Tlie Head is comparatively large and rounded ; the eyes are swollen and 

 prominent. 



The Arms are unequal, the order of length being 3, 4, 2, 1, and on an average about 

 half as long as the body ; the first are very small, slender, and rounded ; the second 

 have a prominent ventro-lateral angle, not amounting to a keel ; the third have a distinct 

 web on the outer aspect of tlie distal portion, which is continued backwards as a faint 

 ridge, which joins the web lying along the dorsal lateral edge of the fourth. The suckers 

 are in two series, and vary in size in accordance with the arms on which they are situated ; 

 they are subglobular and oblique. The horny ring bears about ten broad, closely set, 

 square-cut teeth (fig. 8). The hectocotylus was not present in the Challenger specimen, 

 which was a female ; but in some examples in the Copenhagen Museum, Professor 

 Steenstrup pointed it out to me, as usual, on the left ventral arm ; the distal suckers of 

 the ventral series only are modified into conical papillae, some of which bear a minute 

 sucker at their tips (fig. 10). The umbrella is absent ; the buccal membrane is 

 well developed and has the usual seven points, each of which bears a few small suckers 

 (occasionally only one). The outer lip is thick, thicker than the inner ; both are cut 

 up into papillae along the edge. 



^ Journ. de Conch., sdr. 3, vol. xii. p. 25, 1872. 



