8 SYDNEY J. HICKSOX AND F. H. GRAVELY. 



Although Eadendrium insigne appears to be widely distributed in the seas of the 

 Northern hemisphere, it is not included in Hartlaub's list (10 : pp. 505-509) of 

 Southern species. 



SUB-FAMILY BIMEKIINAE. 



GENUS STYLACTIS. 



The generic name Stylactis was introduced by Allman for two species referred 

 to the genus Podocoryne by Sars (P. fucicola, and a variety of P. earned). The 

 principal characters that distinguish the genus from Podocoryne are (l) The 

 absence of any superficial coenosarc covering the hydrorhizal plexus ; and (2) the 

 gonophores in -the form of sporosacs instead of free swimming medusse. From 

 Hydractinia the genus is distinguished by the first of these characters, but it agrees 

 with it in the second character. 



Allman placed the genus in his family Bimeriidae, and thus removed it from the 

 neighbourhood of the other two genera. 



The opinion of later writers appears to favour the view that Stylactis is more 

 closely related to Hydractinia and Podocoryne than Allman's classification suggests. 



Bonnevie (5 : p. 485) unites Hydractinia and Podocoryne into one genus, 

 Hydractinia, and Motz-Kossowska (17 : pp. 81-85) includes in the same genus the 

 two species that formed the genus Stylactis of Allman, and has added a new species 

 H. pruvoti from the Balearic Islands, which is intermediate in characters between the 

 species attributed by older authors to the genera Stylactis and Podocoryne 

 respectively. 



We are quite convinced of the general affinities of the three genera, which 

 are indeed emphasised by this collection from the Antarctic Sea in so far as we 

 have a species of Stylactis with dactylozooids of a simple kind, and a species of 

 Hydractinia without dactylozooids, the usual condition being that Stylactis has 

 dactylozooids and Hydractinia has not. At the same time, the hydrorhiza of our 

 two forms is so distinct and the minute characters of the gonophores so different 

 that we have thought it better to retain the generic name Stylactis and keep it in 

 the family Bougainvilliidae for the present. 



STYLACTIS HALECII. 

 (Plate I., figs. 5, 6 ; and Plate IV., fig. 33). 



Locality: McMurdo Bay; February 28th, 1902. Found at depths of less 

 than 20 fathoms. 



A considerable quantity of this interesting species was found encrusting the 

 thicker stems of Halecium arboreum. It arrived in a fairly good state of preservation 

 notwithstanding that the bottle containing it was broken in transit. 



l/f/drosome. The hydranths arise directly from an encrusting hydrorhiza 



