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 Vanhuffen's account of C. 

 sericeum, they probably belong to that species. 



Maas believes that Colobonema sericeum is identical with a Medusa from 

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

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

 of C. sericeum 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. c. thirty-two, 

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

 of Colobonema sericeum. In C. typicum, however, 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. sericeum these are 

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

 typicum they are cylindrical. Maas believes that these differences are, at 

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

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

 specific difference. 



Colobonema sericeum Vanhoffen. 



Colobonema sericeum Vanhoffen, : 02 b , 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. J,, 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 ; I specimen, L8 nun. high. 



Station 4743; 300 fathoms to surface, 2 specimens, l<> and 39 nun. high. 



