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



whose proximal more slender portion is furnished with small closely placed suckers, 

 while the distal part bears much larger ones. 



" They are distinguished, on the contrary, by the much weaker musculature of the 

 mantle (very little more powerful than in Cranchia Reinhardtii) and their more elongated 

 form, more expanded fins one-third to one-fourth the length of the mantle, the great 

 inequality in the length of the arms, and especially the preponderance of the lateral arms 

 over both the ventral and dorsal, both in length and stoutness. When the mantle is 

 divided along the ventral median line two peculiarities are observed : the position of the 

 \-iscera in an aggregated mass far back in the mantle-cavity, with the rectum projecting 

 from it, but so short that the anus with its two appendages lies about midway in the 

 mantle-cavity and far from the base of the siphon ; also the long and broad musculi 

 depressores infundibuli, which extend backwards meeting in the middle line. The 

 formula of the arms 2, 3, 4, 1 . 



" The gladius can be seen through the almost transparent, or at all events translucent 

 mantle, in the form of a long, almost linear streak, until it approaches the base of the 

 fins ; here it expands into a broad lance-shaped blade, whose two margins bend over and 

 form a hollow cone posteriorly. It closely resembles the figure of Conoteiithis given by 

 d'Orbigny."^ 



Tracheloteuthis riisei, Steenstrup (PL XXVIII. figs. 6-12). 



188L Tracheloteuthis Riisei, Stp., Vid. Meddel. nat. Foren. KjoLenliavn, p. 294. 

 1884. VerriUiola gracilis {?), Pffr., CepL Hamb. Mus., p. 22, fig. 28. 



Habitat. — Station 2, Fseroe Channel, H.M.S. " Knight Errant " Expedition, July 

 28, 1880 ; lat. 60° 29' K, long. 8° 19' W.; surface. One specimen. 

 Atlantic, Mediterranean (Steenstrup); Solomon Islands (Pfeffer). 



The Body is cylindrical in its anterior two-thirds and then tapers rapidly to a point. 

 The Jin is very little more than one-third the length of the body, and considerably 

 broader than long; it is cordate in shape and is notched at its anterior insertion 

 (fig. 6). The mantle-margin is transverse, slightly convex dorsaUy. The mantle- 

 connective consists of an elongated cartilaginous groove and ridge in the nuchal 

 region, and of a linear ridge on either side of the mantle fitting into a correspond- 

 ing groove at the base of the sij^Jion ; which is short, subulate and deeply notched in 

 the middle line behind (fig. 7). It is provided with a small valve; and has two 

 long suspensory ligaments connecting it with the head. The furrow in which it lies is 

 shallow. 



The Head is narrower than the body except for the eyes, which in the present 



' Moll, viv., pi. xxxii. figs. 1, 4. 



