SYDNEY J. HICKSON AND F. H. GRAVELY. 



gonophores, if they occurred, could never or very rarely reach the surface of the 

 sea. It is, therefore, noteworthy in this connexion that, although there are eight 

 families represented, not a single species exhibits free swimming medusiform 

 gonophores. The only species in the whole collection with free swimming medusae ' 

 is Obelia geniculata from the Auckland Islands. 



The question whether a particular specimen of zoophyte is or is not the type 

 of a new species must be, to a certain extent, a matter of opinion, or perhaps of 

 prejudice, of the systematic zoologist who describes the collection. The actual number 

 of new species in this collection therefore is not a matter of great statistical 

 importance. We regard, however, ten of the twenty-three sub-glacial species as 

 certainly new to science, and five species as probably new. Four species have only 

 been found elsewhere in Southern seas, one on the coast of California, and three are 

 European. Of the three European species only one Halecium tenellum has 

 hitherto been found in Southern seas. 



The noteworthy features of the collection as a whole are : the large proportion 

 of new species, the absence of any definite new generic type, and the occurrence of 

 three species (excluding Obelia geniculata, which is well known to occur in Southern 

 seas) that are common species on the British coast. 



The most remarkable and interesting species is undoubtedly Hydractinia dendritica, 

 a new species, which we have decided to study in greater detail. The question of the 

 extent of degeneration of the gonophores of the sub-glacial species as compared with 

 that of similar species living in open seas, is one that appears to us likely to furnish 

 some interesting results if carefully pursued. 



In conclusion we wish to express our sense of admiration and appreciation of the 

 services rendered to science by Mr. Hodgson, the biologist of the Expedition, in 

 collecting these Hydrozoa. The work of boring holes in the ice and of patiently 

 dredging under the severe conditions of an Antarctic winter must have been of a 

 nature that demanded extraordinary skill and enthusiasm in the cause of zoology. 



The following is a complete list of the species we have described. They all come 

 from McMurdo Bay, except those with specially named localities. 



There is not sufficient material to make any definite statement as to bathymetric 

 range, but it is noteworthy that several species were found in depths ranging from 

 shallow water down to 130 fathoms. 



GYMNOBLASTEA. 



FAM. BOUGAINVILLIIDAE. 



Periyonimm antarctims, sp. n. 10-130 fathoms. 

 Eudendnum insigne, Hinuks. 10-20 fathoms. 

 Htylactis halecii, sp. n. 2o fathoms. 



FAM. PODOCORYN1BAE. 

 Hydractinia dendritica, sp. n. 5-10 fathoms. 



