vol. l.] Torrey .—Hydroida of tht Pacific (Joust. 61 



tritely from S.polyzonias: there are without exception three teeth 

 and three pieces to the operculum on each hydrotheca. 



The gonosome still remains unknown. (August 1, 1901.) 



Sertularella dentifera, sp. no v. 



PI. VI. Figs. 51, 52. 



Trophosome. Stems slender, flexuous, branched. Branches arising within 

 or in place of hydrothecae ; similar to stem. Hydrothecae free for three- 

 quarters of their length, tubular, slightly enlarged at base; margin redupli- 

 cated, furnished with three moderate teeth forming a triangle with apex 

 nearest stem. 



Gonosome not present. 



Distribution. San Pedro, Cal. 



In size and habit this species resemble*s »S'. conica Allman, and 

 was brought up in the same haul with specimens of the latter. 

 It is represented in the collection by a single stem, with portions 

 of two branches. The mode of origin of its branches — within 

 hydrothecae— places it in Allman's genus Thecocladium. That 

 genus, however, seems to me quite as unnecessary as Synth <ii<in , 

 whose validity is discussed below (p. C2.) 



Sertularella fusiformis, Hiucks. 



PI. VI. Figs. 53,54. 



Sertularia fusiformis, Hineks, Ann. N. H., 1861-2, (3), VIII, p. 253. 

 Sertularella fusiformis, Hiucks, Brit, Hydr. Zooph., 1868, p. 24:'.. 



Distribution. San Francisco, Cal., between tides, (neat 

 Britain, between tides (Hiucks). New Zealand (var. nana, 

 Bartlaub). 



Female gonotheeae with acrocysts, January 22, 1902. 



Sertularella halecina, sp. nov. 



PI. VI. Fig. 55. PI. VII. Fig. 56. 



Trophosome. Stems rising from a creeping stolon, about an inch in 

 length and may branch once or twice. Branches similar to the stem, with 

 two or three annulae at the base of each, and a hydrotheca in the axil. 

 Stem and branches divided by faint oblique nodes, which may often be 

 wanting, into equal internodes. Hydrothecae alternate, one to each inter- 

 uode, aduate at base only; cylindrical, with a slight swelling on the lower 

 side at base and a wide aperture with a smooth everted rim, which may be 

 reduplicated; without operculum. 



Gonosome. Gonotheeae (male) arise from within hydrothecae; long, 



