22 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 4 



purely offensive and defensive zooids (spiral zooids) there was no means 

 of telling from the specimens. 



Spines. — There were no spines. The individual zooids fit into cavi- 

 ties in the sponge skeleton and apparently need no further protection of 

 that nature. 



Distribution. — East of the islands off Navidad Head, 25-35 fathoms. 



Hydractinia hancocki, new species 

 Plate 4, Fig. 18 



Trophosome. — Colonies growing on small-ribbed gastropod shells, 

 with the basal coenosarc forming a loose network, the meshes fitting 

 into the sulci of the shell. There are no definite spines ; sometimes closely 

 crowded, there are brown spheroidal bodies, looking like the basal 

 bodies of real spines. In some colonies, however, none of these was 

 observed. The nutritive zooids are slender, reaching a height of 1.8 

 mm. The tentacles are few in number, 12-16, arranged in one irregular 

 series. 



Gonosome. — The generative zooids are smaller than the nutritive, 

 and the tentacles are reduced in number, commonly 4. The male gono- 

 phores vary in number, up to 7, placed some distance proximal to the 

 tentacles, not in a regular series. The female sporosacs are placed simi- 

 larly to those in the male and are even more irregular in position. The 

 ova are few, with 6 as a maximum. 



Other zooids. — None observed. 



Distribution. — Black Beach, at low tide; Post Office Bay, 12-15 

 fathoms; Stephens Bay, 32 fathoms; west of South Seymour Island, 5 

 fathoms; Sulivan Bay, 6 fathoms; Cartago Bay, 8-12 fathoms; between 

 Charles and Indefatigable islands, 60 fathoms; Gardner Bay, 20 

 fathoms. 



Hydractinia longispina, new species 

 Plate 4, Fig. 19 



Trophosome. — Colony growing from a basal coenosarc, consisting 

 of a close network from which arise several elongated spines. The nutri- 

 tive zooids are long, 3 mm., but rather slender, with numerous (30 or 

 more) long, slender tentacles, not definitely arranged in series. 



Gonosome. — The generative zooids are but slightly reduced in size, 

 if at all; the number of tentacles varies but there is seldom more than 

 half of the number found on the nutritive zooids. The sporosacs are 



