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



several arms owing to the presence of the intermediate web, and might render the whole 

 apparatus a very effective fishing-net. 



The dorsal cartilage (PI. XIII. figs. 1, 2) maybe described as saddle-shaped; it is 

 narrow, thick, and rises up into a prominent angle on the dorsum, while the two sides are 

 flattened out into obovate expansions, which are more prominent anteriorly than pos- 

 teriorly. A thick semi-cartilaginous membrane is attached all round the dorsal surface, 

 and appears to have been reflected over it, and thus to have enclosed a narrow cavity 

 above the cartilage : in Cirroteuthis mulleri a similar membrane seems to have overlapped 

 the posterior surface and to have formed a cavity there. ^ This organ is widely different 

 in form from that of Cirroteuthis mulleri as may be seen at once on comparing PL XIII. 

 figs. 1, 2, with the figures in Eeinhardt and Prosch's Memoir. In both instances, 

 however, the cartilage is entirely free from the sac in which it lies, and the bases of the 

 fins rest upon it near the extremities of the lateral expansions. 



The mangled specimen from Station 298 was at first referred to Stauroteuthis, but 

 with very great hesitation ; firstly because of its lacerated condition, and secondly in 

 consequence of doubts as to the validity of the genus. 



In Verrill's definition there are but few points mentioned which seem to me of generic 

 importance, and of these a large proportion are also common to Cirroteuthis, for instance, 

 the opening sentence — " Allied to Cirrhoteuthis, but with the mantle united to the head 

 all around, and to the dorsal side of the slender siphon, which it surrounds like a close 

 collar, leaving only a very narrow opening around the base of the siphon, laterally and 

 ventrally " ^ — is quite misleading, and would not have been written if the author had had 

 the opportunity of examining a specimen of Cirroteuthis in good condition, for he would 

 then have seen that these characters, upon which he relies for distinction, are common to 

 both genera ; the mistake has no doubt arisen from his having had for comparison onl}^ 

 the figures of Eschricht," which exhibit the mantle as gaping widely open and exposing 

 the gills ; a condition only seen in specimens whose tissues have become loosened and 

 stretched in consequence of defective preservation. The excellent drawing of the animal 

 in a living condition by Madame Eudolph, published by Eeinhardt and Prosch,* would 

 have shown Professor Verrill the true state of the case, especially when taken in conjunc- 

 tion with their clear description of the arrangement : — " Head and body are united to 

 the greatest extent possible, so that there only remains a horse-shoe-shaped aperture 

 closely surrounding the funnel in the ventral median line" {op. cit., p. 11).^ 



The points which are really diagnostic between the two genera, if only reliance can 

 be placed upon them, are the following: — (1) "Dorsal cartilage forming a median 



1 Om Seiadephorus Mulleri, tab. iii. figs. 1, 2, 3. 2 Cepli. N. E. Amer., p. 382. 



3 Nova Acta Acad. Cces. Leap. -Carol., torn, xviii., tab. xlviii. * Om Seiadephorus Mtilleri, tab. i. 



^ Professor Steenstrup, who gave Dr. Eudolph a preliminary acquaintance with the Mollusca of Greenland before 

 his departure to that country, tells me that this account of the form of the mantle-opening was confirmed by Dr. and 

 Madame Rudolph in conversation with him. 



