148 THE VOYAGE OF H.M.S. CHALLENGER. 



From these facts we sliould be inclined to suppose that Sepia pfefferi and Sejpia 

 tuberculata stand in a nearer relation to each other than does either of them to 

 Hemisepius, which is clearly marked off by the presence of only two series of flattened 

 suckers on the sessile arms, and the broad shape of the ventral pair of these ; by the 

 form of the tentacular club, and by the two rows of glandular pits down its ventral surface. 



The three forms seem to constitute together a very aberrant branch of the group, 

 but w^e have not at present sufiicient knowledge to interpret their precise relations to 

 the more ordinary forms. Indeed the problem of the natural relationship of the various 

 species of Sepia is far from having been satisfactorily worked out. The shells, which 

 seem in many respects the organs most likely to lead to a solution, can be arranged in series 

 increasing or decreasing in complexity, and there are several interesting fossil genera,^ 

 which help to bridge over the gulf separating Sepia from the Belemnites, but an arrange- 

 ment of the species based upon the shells does not agree with one based upon the form of 

 the tentacular club, or other parts of the animal's organisation, so that we are hardly 

 justified in regarding it as natural 



Since the- above remarks were written I have received, by the kindness of Dr. 

 Appellof, a copy of his paper on Japanese Cephalopoda,^ which contains the description 

 of a new species, Sepia tullhergi, closely related to the present form. The two agree in 

 the short rounded form of the body, the slight convexity of the anterior dorsal border of 

 the mantle, the depth of the siphono-pallial articulation, the absence of the linear ridge 

 and groove in the nuchal articulation, the disparity in the sizes of the tentacular suckers, 

 and in the form and structure of the shell. 



Such being the case, there is no doubt that Sepia tullhergi belongs to the group to 

 which I have given the name Metasepia. 



There are a number of details in which the specimen obtained by the Challenger 

 differs from that described by Appellof, so that it is impossible to regard them as other 

 than distinct species. 



In Sepia pfefferi the pits at the base of the funnel for articulation with the mantle are 

 deepest in the middle, not at the anterior end as in Sepia tullhergi ; there is no trace of any 

 tubercles on the back or head ; the teeth of the suckers on the sessile arms are finer and more 

 acute, not so broadly triangular, as indicated in Appellof s figure (pl.ii.fig. 13); the tentacles 

 are decidedly shorter and the large suckers on the club are not so conspicuous (compare 

 pi. ii. fig. 8, with PI. XXI. fig. 7 of the present Report, where indeed they are hardly 

 large enough) ; the denticulation of their horny rings, too, is much finer and not so regular. 



The shell agrees in almost every particular with Appellof's description, except that 

 the posterior extremity, although somewhat thickened, does not give rise to any structure 

 at aU like the horny lamella indicated by his figure (pi. ii. fig. 11, a). 



1 For interesting remarks on some of these see Lankester, Quart. .Town. Micr. Sci., N.S., vol. xiv. p. 372, 1874. 

 - K. Svetisk. VetensJc. Akad. Handl, Bd. xxi. No. 13, pp. 1-40, pis. i.-iii. 



