On the Tentacles of an Antarctic Siphonophore. 25 



V. Scotia Collections. — On the Tentacles of an Antarctic 

 Siphonophore. By John Eennie, D.Sc, University of 

 Aberdeen. [Plate II.] 



(Received 12th December 1904; read 19th December 1904.) 



Amongst some material kindly entrusted to me by Mr 

 W. S. Bruce for examination, there occurred a number of 

 long vermiform structures, which, on a preliminary examina- 

 tion, appeared both from external characters and consistency 

 suggestive of a Polyzoon of the group Ctenostomata. A 

 closer investigation, however, has revealed the fact that 

 these bodies are the separated tentacles of an unknown 

 Siphonophore. They present one or two features of interest, 

 which, considering the limited number of forms belonging 

 to the group which are known from Antarctic regions, I 

 have thought worth recording. 



Professor J. Arthur Thomson has quite recently,^ from 

 material of the same collection, described the detached 

 gonostyles of a Siphonophore. He agrees with me in 

 thinking that they must be referred to a different type 

 from that to which these tentacles belong. The localities 

 and dates of capture are different, the sizes of the two organs 

 represented are disproportionate, and, in particular, such 

 histological characters as could be compared, particularly 

 the cnidoblasts, show distinctive features. 



The tentacles were taken in the drifting net (1 to 100 

 fathoms) on 5th March 1904, in 72° 31' S. lat., 19° 00' W. 

 long. The surface temperature was 29°*2 F. 



In all there are thirteen parts, nearly every one of which 

 is obviously incomplete. The longest piece measures 4 feet 

 3 inches in length, the others range from 2 feet to 3*3 inches. 

 They are circular in section, are thicker at the attached end 

 than at the free, to which they taper very gradually (PI. II. 

 Fig. 1). The extreme diameter measurements of all the 

 pieces are 7 mm. and IJ mm. respectively. The surface is 

 of a pale brown colour, and is covered by very minute, 

 approximately oval or circular, elevations closely set 



^ Proceedings of this Society, 28th November 1904. 

 VOL. XVI. D 



