with Observations on Australian Hydroids. 81 



The distinguishing feature in this genus is the bifurcation 

 of the pinnse. In both known species there is seated in 

 each bifurcation a hydrotheca without nematophores. One 

 of them is further remarkable for having two sarcothecse 

 side by side in place of the usual anterior one. 



POLYPLUMARIA, Sars, modified. 



Hydrocladia pinnatel}^ arranged, with an accessory 

 hydrothecal ramulus springing from the proximal internode 

 of each ; sarcothecse not attached to the hydro thecse. 



Gonangia not provided with phylactocarps. 



The genus Polyplumaria of Sars was characterised mainly 

 by its doubly pinnate ramification, while Diplopteron 

 (Allman) was distinguished by tlie same feature, and also 

 by the possession of two pairs of lateral sarcothecEe above 

 the hydrotheca. In the " Challenger" Report the species 

 are united under Polyplumaria, and the generic characters 

 modified, making the essential feature the possession of aa 

 accessory ramulus bearing hydrothec?e, and springing from 

 the proximal internode of each pinna. According to Sars' 

 figures, his Plumulavia gracillima has the same peculiarity, 

 and our P. cornuta also has the secondary ramulus, though 

 in an aborted or rudimentary form. 



MoNOSTiECHAS, Allman, 



Hydrocladia arranged uniserially; sarcothecae not attached 

 to the hydrotheca. 



Gonangia not provided with phylactocarps. 



In the only known species of this genus the hydrocladia 

 are arranged in a single series along the distal side of the 

 branches, somewhat as in the Gymnoblastic genus Pennaria. 

 The minute structure is like that of Pluniularia Catharina.. 



Antennularia, Lamarck 

 {Nemertesia, Lamouroux.) 



Hydrocladia disposed along three or more sides of the 

 stem; sarcothecse not attached to the hydrotheca. 



Gonangia not provided with phylactocarps. 



The hydrocladia of Antennularia have been usually 

 described as verticillate. The above definition will include 

 all the species now known, among which are the Heteropyxis 



G 



