196 HYDROIDS FROM NEW SOUTH WALES.* By E. a. Briggs, B.Sc, Zoologist, Australian Museum, Sydney. ( C oinmuiiicated by A. R. McCidloch.) (Plates xxx.-xxxi., and Text-fig. 1.) i. Introduction. In 1911 Dr. Ritchie described, under the name of Sertularella longitheca Bale, var. robusta, several hydroid specimens obtained by the " Thetis" Trawling Expedition off the coast of New South Wales. He had only sterile specimens for examination, but several additional colonies bearing gonangia occur among some Polyzoa, which were dredged by the same Expedition in New-castle Bight, N.S.W., at a depth of 26-40 fathoms. In view of the totally distinct gonangia, these specimens cannot be regarded as belonging to a variety of Sertularella longitheca. The char-acters are so distinct from those recorded, that it is necessary to raise Ritchie's variety to specific rank. The name robusta is preoccupied in the genus, and, therefore, I substitute Sertidarella ritchiei. The second species here under discussion is represented in the Australian Museum collection by some fine colonies from Marou-bra Bay, near Sydney, N.S.W. ii. Descriptio7i of the Species. Order Calyptoblastea. Family SERTULARID^. Genus Sertularella Gray. Sertularella ritchiei, nom.nov. (Plate XXX., tigs. 1-2; Plate xxxi., fig.2; and Text-fig.].) Sertularella longitheca Bale, var. robusta Ritchie, Mem. Austr. Mus., iv., 16, 1911, p.841, PI. Ixxxviii., fig.8. * Contributions from the Australian Museum.