A COLLECTION OF HVDKOIDS. 283 



has described under the name Halocordyle cooperi a 

 hydi'oid which occurs along the Zululand and Natal coasts. 

 It differs from the description of Pennaria austral is Bale 

 in the number, and arrangement in whorls, of the capitate 

 tentacles. Definite variations in these characters were found 

 to occur in different colonies of the Natal hydroid, and it is 

 now seen that a series of gradations, leading to a symmetrical 

 arrangement in whorls, occur in the different species of 

 Pennaria. 



The main character which distino-uishes the o-enus Halo- 

 cordyle from that of Pennaria is the verticillate arrange- 

 ment in the former of the capitate tentacles ; but an examina- 

 tion of the following table will show that it is scarcely 

 necessary to retain the genus Halocordyle. 



Filiform Capitate 



tentacles. tentacles. 

 Pennaria gibbosa ^</rfss('z,' America . 12 32 scattered. 



,, symmetrica C/«/-^-e,'^ America 14-18 .30 „ 



,, cavolinii Ehrenberg,^ Europe 12 20 ,. 



,, an strali s 5«/e,^ Australia . 7-12 9-14; 4. oral 



whorl ; .5-10 

 scattered below 

 ., .. var. cooperi, Natal . 8-10, 8-13; typically 



typically 8 4 oral and 4 

 basal tentacles 

 alteraating. 

 ,, adanisia von Lendenfeld,'^ 24 4 oral and 4 



Australia basal alternating'. 



Halocordyle tiarella Ayres,'^ N. America 12? 6 oral, 6 basal. 



„ australis Bale,^ Australia 8-10 4-5, oral whorl, 



rest scattered. 



' Allman, G-. J., ' A Monograph of the Gymnoblastic Hydroids,' Part 

 II, pp. 363-370. 



^ Bale, W. M., " On some New and Rare Hydroida in the Australian 

 Museum Collection," ' Proc. Linn. Soc. N. S. Wales,' vol. iii, 1888, p. 747. 



^ Bale, W. M., ' Catalogue of the Australian Hydroid Zoophytes.' 

 1884, p. 45. 



^ Lendeufeld, R. von, " The Australian Hydromedusa*," Part V, 

 ' Proc. Linn. Soc. N. S. Wales,' vol. v, 1884-5, p. 595. 



■' Bale, W. M., " Further Notes on Australian Hydroids," ■ Proc. 

 Roy. Soc. Victoria.' 1893, p. 94. 



VOL. 1, pAirr .'). 21 



