116 



THE VOYAGE OF H.M.S. CHALLENGER. 



perhaps be regarded as only a variety of it; still it seems quite easy to distinguish 

 well-grown specimens of the two species from each other, as follows : — 



Rossia oweni. 



1. Attains rather greater dimensions, in the largest 



specimen in my collection (?) the length of the 

 body is 50 mm. 



2. The body is more elongated, the breadth being 



55 to 65 per cent, of the length. 



3. The tentacles are shorter. 



4. The tentacular suckers are slightly larger. 



Rossia macrosoma. 



1. In the largest specimens I have seen the length 



of the body was from 30 to 35 mm. 



2. The breadth is 70 to 75 per cent, of the length. 



3. The tentacles are longer. 



4. The tentacular suckers are not quite so large. 



The most accurate of the descriptions published is that of Loven quoted above, 

 the original diagnosis of Ball being extremely incomplete and misleading in the state- 

 ment that the suckers are in three rows; they are really in four, but sometimes 

 (especially in the males) so irregular that on casual inspection only three seem to be 

 present. 



The only figure of this species hitherto published is that of Forbes and Hanley 

 (loc. cit.) which leaves much to be desired ; the tentacular club in particular is very 

 inaccurate (compare PI. XV. fig. 6 with pi. sss.). The central figure of PI. XV. is 

 taken from a fine specimen ( ? ) obtained by H.M.S. " Porcupine," while figures 2 and 

 5 are from a male captured ofi" Wexford, the only specimen of that sex which has 

 come into my hands. The teeth of the large tentacular suckers are very irregular (see 

 figs. 7 and 9) ; the papillary area which immediately surrounds the horny ring consists 

 of two rows of obliquely truncated conical papillae (seen in profile in fig. 8), outside which 

 is a layer of chitinous material with somewhat irregular closely set radial markings. 



This species would seem, judging from the literature of the subject, to be rather 

 rare, each of the previous observers having recorded only one specimen, but several 

 unrecorded examples are in the Museums of Copenhagen and Gotheborg, and there can 

 be little doubt that it would have been much more frequently mentioned had it not 

 been wrongly identified with Rossia macrosoma. A considerable number of specimens 

 were trawled last summer by the " Medusa " during the sojourn of the Scottish 

 Marine Station at Millport in the Firth of Clyde. 



Rossia glaucopis, Loven. 



1845. Rossia glaucopis, Loven, Ofversigt k. Vetensk. Akad. Forhhandl., p. 121. 



1869. Rossia papilUf era, Jeffreys, Brit. Conch., vol. v. p. 134. 



1878. Rossia glaucopis, Sars, Moll. Eeg. Arct. Norv., p. 337, pi. xxxii. 



Habitat. — Station 65, north west of the Shetland Islands, cruise of H.M.S. 

 " Porcupine," 1869; lat. 61° 21' N., long. 3° 44' "W.; 345 fathoms. One immature 

 specimen. 



