COLOBONEMA SERICEUM. 133 



it is evident that this character is subject to considerable individual variation, 

 and is not of specific importance, as Maas has suggested (: 05, p. 53). Since 

 in other respects, i e. general form, form of the gonads, number of tentacles, 

 and color, the " Siboga " specimens agree with Vanhoffen's account of C. 

 se/'iceum, they probably belong to that species. 



Maas believes that Colobonevia sericetim is identical with a Medusa from 

 the Gulf of California, described by him under the name Homoeonema 

 typimm ('97, p. 22, pi. 3, figs. 1-3), and that the name C. iypicmn instead 

 of C. sericeimi should therefore be employed. I agree with Browne, however 

 (:06), in thinking that the connection between these two forms is doubtful. 

 All recent examples show that the number of tentacles, i. e. thirty-two, 

 and the type of their succession is one of the most constant characters 

 of Colobonema sericeimi. In C. typicum, how^ever, according to Maas's original 

 figures, there are not only many more tentacles, but a variable number in 

 different octants (three to seven between every two radial canals). The 

 shape of the gonads, too, is different, for while in C. sericeimi these are 

 linear, and occupy almost the entire length of the radial canals, in O. 

 ti/picum they are cylindrical. Maas believes that these differences are, at 

 least in part, due to the poor condition of the material from which C. 

 typtciim was described, but they appear to me quite sufficient to indicate 

 specific difference. 



Colobonema sericeum Vanhoffen. 



Colobonema sericeum Vanhoffen, :02'', p. 57, taf. 9, fig. 1, taf. 12, figs. 39-42; Browne, 



: 06, p. 172. 

 ? Colobonema typicum Maas, : 05, p. 53, taf. 10, figs. 62-65. 



Plate 2, Figs. 4, 5 ; Plate 45, Fig. 12. 



Station 4646 ; 300 fathoms to surface ; 1 rather fragmentary specimen. 



Station 4655 ; 300 fathoms to surface ; 1 specimen, fragmentary, 20 mm. 

 high. 



Station 4661 ; 300 fathoms to surface ; 1 excellent specimen, 22 mm. high. 



Station 4670 ; in trawl from 3,209 fathoms ; fragments. 



Station 4679 ; 300 fathoms to surface ; 1 excellent specimen, 35 mm. high. 



Station 4715 ; 300 fathoms to surface ; 1 fragmentary specimen. 



Station 4721 ; 300 fathoms to surface ; 1 specimen, 18 mm. high. 



Station 4743 ; 300 fathoms to surface ; 2 specimens, 10 and 39 mm. high. 



