28 SYDNEY J. HICKSON AND F. H. GRAVELY. 



Up to a height of about 150 mm. the colony consists of only four or five thick 

 (7 mm. in diameter) and occasionally anastomosing stems, bearing a few thinner 

 (3 mm. in diameter) branches which are themselves pinnately branched. Above this 

 region the thick stems branch much more profusely and somewhat pinnately, bearing 

 numerous thinner branches whose method of further ramification is always pinnate. 



The ultimate branches (hydrocladia) are jointed, the internodes being ' 6-1 1 mm. 

 in length and about 0'4 mm. in diameter. Each internode bears on one side a sino-le 



o o 



hydrotheca (hydrophore) adnate throughout its whole length, and supporting the 

 base of a hydranth 2 mm. in length (fig. 24, hyd.), and on the opposite side a long 

 serpentine dactylozooid (sarcostyle) 1'5 mm. in length and about 0*15 mm. in 

 diameter (fig. 24, d.}, supported at the base by a nematophore (sarcotheca) 0'15 mm. 

 in length and about O'ISmm. in diameter. 



At the extremity of the dactylozooid there is a battery of nematocysts. In the 

 specimens many of the dactylozooids and nematophores are broken off, but there is 

 little doubt that they are usually, if not regularly, present in the living colony in the 

 position assigned to them. The dactylozooids are very similar to those figured by 

 Hincks for Ophiodes mirabilia, although not so clearly "knobbed" at the extremity. 



The hydranths are of the typical Halecium form. The hypostome is surrounded 

 by a circle of about twenty tentacles each about 5 mm. in length. 



Gonosome. The gonothecae together with some nematophores occur in 

 " coppinia " masses (fig. 28) on the stem and branches. These " coppinia " masses 

 are oval or spherical, densely branched and tangled clumps, 25 x 25 mm. to 

 GO X 30 mm. in size, having a rough resemblance to the " bedeguar " galls on the 

 stem of the wild rose. The delicate dichotomously ramified branches of these 

 masses bear dactylozooids and nematophores (fig. 29, (/. and iip/t.) similar to those of 

 the other parts of the colony, and numerous paired gonothecae (fig. 29, fftfi.), 

 I'O x 0'7 mm. in size, which curve sharply backwards, terminating in a hook-like 

 process at the extremity of which is the gonothecal mouth. 



The type of this species was found at Kerguelen in 1874. 



HALECIUM TENELLUM. 

 Halecium tenelhtm, T. Hincks, Brit. Hyd. Zoophytes (18G8), p. 22C, pi. xlv., fig. 1. 



Localities. W.Q., McMurdo Bay, February 20th, 1902 ;- 20 fms. W.Q., Flagon 

 Point, January 17th, 1903 ; 10-20 fms. W.Q., Flagon Point, February 23rd, 1903. 

 W.Q., off cable, February 17th, 1904. W.Q., D net, June 15th, 1902. 



This widely distributed little Halecium appears to be fairly common in 

 McMurdo Bay. It is found on sea-weed, Alcyonium paesftleri, on Halecium arboreum, 

 and on other hydroids. 



Hydrosome. The delicate little colonies are about 10 mm. in height and 

 spring from a creeping hydrorhiza. The hydrocauli are monosiphonic, irregularly 



