Australian Hydroids. 857 



Dr. A. Brauer,^ have established the fact that another European 

 species exists, sharing with //. oligaciis the stalked condition, but 

 differing from it in several particulara not recognised by the older 

 observers; and the description renders it probable that our com- 

 mon species may be associated Avith this new form, unless, which 

 is not unlikely, it may prove distinct from both. It is also possible 

 that more than one species may be represented among the forms 

 which we have been accustomed to call //. oligactis. 



Trembley, in his famous memoir, described three species, which 

 he called the first, second, and third species (according to the 

 order in which he observed them), and to British observers, at 

 least from Johnston onwards, these have been known respectively 

 as H. viridis, H . vulgaris, and H . oligactis. Continental observers, 

 have more commonly, in disregard of priority, referred to the two 

 last as H. grisea and H. fusca; in many cases, however, they have 

 confused the species, and, as Bedot remarks, have named their 

 specimens solely according to their colour or their abundance^ 

 calling them grisea, fusca, or carnea, according as they are grey, 

 brown, or rose, and vulgaris when they are very abundant. Brauer- 

 himself, in an earlier paper, referred to the species subsequently 

 found by him to be new, as H. fusca, and called the true //. fusca 

 or //. oligactis, H. s]). In his later paper he corrects this, and 

 reduces the European species to four, namely, H. viridissima, 11. 

 vulgaris, H. oligactis, and //. 'polyims. In regard to the first 

 three, therefore, he comes into line with British observers, except 

 that he errs in using the name E. viridissima instead of K. viridis. 

 The newly established species, which he calls E. ijolypus Lin., is 

 not Linne's H . poh/pus, as shown by Bedot, ^ who names the species 

 H. hraueri. 



Annandale,* in his paper on the common hydra of Bengal, has 

 described under the name of //. orientalis a species which he finds 

 very nearly allied to //. oligactis (called by him //. diaecia), but 

 which he considers distinct. It is abundant in India, and is the 

 only species which he has found there. 



Von Lendenfeld,'' in 1885, descril>ed //. heractinella from a pool 



1 A. Brauer— Die Bennennnn<f und Unter8cheidun;u' der ffi/dra artau. Zool. Anz., Bd. xxxiii.^ 

 8. 790, 1908. 



2 A. Brauer— fiber die Entwickliuijr von Ifi/dra. Zeitscli. f. wisseiisch. Zoolo},'le, lii. 2, S. 16». 

 1891. 



3 M. Bedot Sur la Nomenclature des Ilydres. Zool. Anzei^r , Bd. xxvix.. No. 19-20, 1912 



4 N. Annandale. The Conunon Hydra of Benjral. Mem. Asiatic Soc. of Bengal, I., No. 16^ 

 p. 339, 190«. 



5 R. von Lendenfell. II i/d ra hexaethieUa, novn s]^ei]i'H. I'roc. I-inn. Soc. N.S.W., x., pt. 4,. 

 p. 679, 188.S. 



