x.i iui-11 y n:s. 



atta. hc.l t< tin- >t-ms <>1" //-//.( iiini iirlx'i-i-iiiH. The character of the bottom on which 

 it - -u|.|Kirt grows is described as stony, gravelly, or very rough ground (Flngon 1't. ). 

 'I':..- qpMstt 'iiti'T- ti"Hi in"-! "t tin- >paciM "t /''.' ..... m >" taraag Bud 



On this a4fount it might be placed by dome authorities in Allinan's genus 

 II ////./, I. in for reasons that have recently been urged by Motz-Kossowska 

 (17 : pp- 68-71) we are of opinion that Wriyhtia should be merged with J'erii/tmimuM. 

 In this particular case the reasons for disregarding the genus Wriyhtia seem to be 

 jwrtii-ularly strong. The size of the colonies and of the individual zooids being much 

 greater than in the only known species of Wrightia, the specimens would, in the 

 absence of the gonophorcs, le undoubtedly referred to the genus Periyonimus. If 

 Pfrit/tmimu* shares the power or possibility that some other genera of gymnoblastic 

 hydroids undoubtedly possess of variation in the character of the lil>eratiou of the 

 gonophores, being in some cases phanerocodonic and in others adelocodonic, we should 

 at least expect that the adelocodonic variation or condition would occur iu specimens 

 living in an arm of the sea such as McMurdo Bay, that is for so many months in the 

 year covered with ice. 



Ili/drofome. From the ramifying hydrorhiza attached to the Halecium several 

 unbranched or occasionally slightly branched hydrocauli arise (fig. 1). They attain to 

 a height of about 8 mm. Many of the hydrocauli appear to be simply unattached 

 branches of the hydrorhiza, and even the pedicels of the gonophores occasionally give 

 off branches of indefinite function and power of growth. 



The transition from hydrocaulus to hydranth is gradual, the length of each 

 hyilntnth being about 1 mm. The hypostome is conical and is surrounded at its base 

 by a circlet of about 10 filiform tentacles each about 0*6 mm. in length. The 

 perisarc is continued as an exceedingly thin film over the hydranth as far as the base 

 of the tentacles. The hydrant hs vary considerably in shape (fig. 3) and are probably 

 very contractile. 



Gonotome. The gonophores are situated on short pedicels which, in the case of 

 the female, are thickened distally. The colonies appear to be invariably dioecious. 

 In both sexes the gonophore is a degenerate medusa. In both sexes the gonopbore 

 is protected by a thin layer of perisarc. It is larger in the female than in the male 

 (1-1 mm. x 0*9 mm. in the female, and 0*9 mm. x 0*7 mm. in the male). 



In the female gonophore there is a large sub-umbrella cavity (fig. 3, *M.C.), the 

 manubrium is well developed and has a well-marked endoderm cavity. 



In the young gonophore there is a distinct endodcrmal layer of cells and 

 mesogloea in the umbrella, but in the adult gonophore (fig. 32) these are reduced 

 to a non-cellular mesogloea except at the margin, where a cord of cells represents 

 the ring canal. There are no radial canals in the adult gonophore. 



In the male gouophore the sub-umbrella cavity is completely filled with sperm 

 cells (figs. 2 and 32, sp.). 



