406 THE AUSTRALIAN HYDROMEDUS^E, 



2. GENUS. SERTULARIA. Hincks. 



Stems arising from a creeping stolon. Trophosomes placed 

 biserially on the stem and inserted in it, without Operculum. 



Weismann (1) describes the structure of one species. Of the 

 histology not much is known. The morphology of the Gonosome 

 is described by Allman (2.) 



SERTULARIA FERTILIS. Nov. sp. 

 Plate VII., fig. 4, 5. 



The stems of the pinnate colonies attains a height of 8 cm. The 

 Pinnee are inserted alternately. They are from 10-14 mm. long. 

 The Trophosomes are alternate, and the stem of the Pinna has a 

 zi^-zag shape, making room as it were for the Hydrothecse to 

 situate themselves in a straight line. The Hydrothecae stand 

 close together, and are somewhat wedge-shaped, with seini-circular 

 opening from the exterior margin of which teeth protude. The 

 opening is directed forward. The Hydrothecae can be considered 

 as semi-immersed. 



The Gonophores are transformed Polyps of stem and Pinna?. At 

 the proximal end of each Pinna, one Polyp becomes a Polypostyle, 

 and there are also Gonophores between the Pinna? on the stem, 

 one in each internode. 



I found this Sertularia at Timaru, East coast of New Zealand, 

 it bears Gonophores in April. 



SERTULARIA IRREGULARIS. Nov. sp. 



Plate VIII., fig. 6. 



I have named a Sertularia, i-elated to Kirchenpauer's Dynema 

 Grosse-dentata, S. irregularis, from the great individual irregu- 

 larities which I have met with in this species. 



( 1 . ) A . Weismann. Die Eutstehung der G eschlechts zellen bei den Hydro- 

 meclusen. Seite, 169. 



(2.) J. Allman, A Monograph of the tubularian, etc., Hydroids. Vol. I, 

 p. 50. 



