Papers. '21 



specimens described by Dr. Benham are representatives of H. vulgaris. 

 though this cannot be decided with certainty till they have been examined 

 more closely. The large reddish -brown form noted by Hamilton will pro- 

 bably also belong to this species. The light-brown species mentioned above 

 as found at Dunedin, Chr'stchurch, &c. appears to belong to the well- 

 known brown Hydra of Europe, commonly referred to as H. fusca. This 

 should, however, be called H. oligactis, this being the name first given to 

 rhe species by Pallas. It seems to be the most common species in New 

 Zealand, having been seen in Christchurch, Wellington, Auckland, and 

 Dunedin. Coughtrey's species evidently belongs here too. 



The New Zealand species now known of Hydra, then, arc H. viridis. 

 H. vulgaris, and H. oligactis. 



Hydra viridis Linn. 

 Hydra viridis Linn.. Sys. Nat.. 12th ed., p. 1320, 1767 ; Johnston, British 

 Zoophytes, p. 121." 1847 ; Hincks, British Hvdroid Zoophytes, p. 312. 

 1868:' Hickson, Camb. Nat. Hist,, vol. 1, p. 256. 1906: Brauer, 

 Zool. Anz., vol. 33, p. 790, 1909. 



Dr. Brauer says that the correct name for this species should be 

 //. viridissima Pall. (1766), but the name H. viridis is so well known and 

 commonly accepted that it would be inconvenient to alter it ; and, more- 

 over, it was used by Linnaeus for this form in the 10th edition of the Systema 

 Naturae, though not definitely as a specific name. In this edition Linnaeus 

 gave all the forms of Hydra under the one name, H. polypus, and it was not 

 until the 12th edition that he divided them up into separate species. 



Hickson describes this species thus : " Colour grass-green. Average 

 number of tentacles, eight. Tentacles shorter than the body. Embryonic 

 chitinous membrane spherical and a 7 most smooth." 



The specimens from the River Avon agree closely with the descriptions 

 i^iven by Hickson. Johnston, and Hincks. The species is now known in 

 New Zealand from Christchurch and Auckland. 



? Hydra vulgaris Pallas. 

 ? Hydra vulgaris Pallas, Elench. Zooph., p. 30, 1766 ; Hickson, Camb. 

 Nat. Hist,, vol. 1, p. 256, 1906. Hydra (" reddish-brown species "). 

 Hamilton, Trans. N.Z. Inst,, vol. 12, p. 303. 1879 ; Benham, Proc! 

 N.Z. Inst., 1909, p. 128, 1910. 



Hickson's description is as follows : " Colour orange-brown. Tentacles 

 rather longer than the body, average number six. Embryonic chitinous 

 membrane spherical and covered with numerous branched fpines." Brauer 

 adds that the proximal end of the body is not narrowed into a stalk, that 

 four kinds of thread-cells are present, and that the ammal is hermaphrodite. 



Habitat. — Shag Valley, Dunedin ; Petane Valley, Napier. 



I have not seen specimens of this species. 



Hydra oligactis Pallas. 



Hydra oligactis Pallas, Elench. Zooph., p. 29, 1766 ; Johnston, British 

 Zoophytes, p. 124, 1847 ; Hincks, British Hydroid Zoophytes, p. 315, 

 1868 ; Hickson, Camb. Nat, Hist., vol. 1, p. 256, 1906 ; W. M. Sale, 

 Cat. Austral. Hyd. Zooph., p. 187, 1884 ; Brauer, Zool. Anz., vol. 33, 

 p. 792, 1909 ; H. fusca Linnaeus, Sys. Nat,, 12th ed., p. 1320. 1767 ; 

 H. viridis Farquhar, Trans. N.Z. Inst,, vol. W. p. 468. 1896 : Hutton. 

 Index Faunae N.Z.. p. 321. 1904. 



