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Show 526 ON THE PLANKTON OP THE FAEROE CHANNEL. [May 18 those of T. riisei, the shape of the fin is markedly that of T. hehnii this is well brought out by Hoyle's figure, which shows a distinctly rhomboid fin. A specimeu of T. hehnii was described by Weiss ', which agrees almost exactly with the diagnostic characters given above for that species. The following table exhibits the dimensions of my specimens the '_ Knight Errant' specimen described by Hoyle, and the Messina specimen described by Weiss, expressed in percentages of mantle length:- ' Research.' Length of mantle in mm. 23 Breadth of mantle . Length of fin Breadth of fins . . . Length of arm 1 . 2 . 3 . 4 . Length of tentacle. . •38 •34 •56 •21 •56 •47 •34 •91 'Knight Errant.' 32 •25 •40 •59 •24 •56 •46 •40 1-00 Messina. 21 •28 •38 •14 •33 •28 •19 •61 So far as this goes it is fairly obvious that the ' Knight Errant' and 'Eesearch' species are the same, and different from the Messina species ; the dimensions further point to an accurate determination by Hoyle and Weiss of their respective species. I have therefore assigned m y specimen to T. rllsel, although the shape of the tail-fin is distinctly that of the other species. Dimensions in millimetres :-end of body to margin of mantle, 23 ; breadth of body, 9 ; length of fin, 8 ; breadth of conjoint fins, 13; arm i, 5 ; arm ii, 13; arm iii, 11; arm iv, 8 ; tentacle, 21. The animal was of an absolutely glass-like transparence, except for the two staring black eyes and a black mass posteriorly (? ink-sac). When it had been killed, scattered chromatophores became more obvious, notably four, symmetrically placed on the dorsal surface of the head, and a line of smaller ones along the median dorsal line of the mantle ; they were of a deep claret-colour. As Hoyle 2 pointed out, and was corroborated by Jatta3, Trache-loteuthls is a member of the subfamily Ommastrephlnl; the latter author refuses, however, to accept the suggested identification of Tracheloteuthls wdth Verrllllola = Eniomopsls, as the four species described under these two genera are members of the Taonoteuthi. Distribution:- (1) Faeroe Channel-60° 29' N., 8° 19' W., surface ('Knight Errant'). (2) Faeroe Channel-60° 2' N., 5° 49' W., 100 to 0 fathoms (•' Eesearch '). (3) Atlantic, Mediterranean (Steenstrup). 1 Quart. Journ. Micr. Sci. xxix. pp. 75-96. pis. viii.-x. 2 Loc. cit. 3 Fauna e Flora Golf. Neapel.-I Cefalopodi (Sistematica), p. 112. |