BY W. M. BALE. 785 



and partly downwards, margin not everted, an incomplete partition 

 extending some distance into the neck, from just below the orifice. 



Hab. Botany. 



This species is very closely allied to P. compressa, but may be 

 distinguished by the more slender hydrosoma, the rounder basal 

 part of the hydrotheca, the large supracalycine sarcothecae, the 

 absence of the intrathecal ridge, and by the margin of the hydro- 

 theca being less elevated above the top of the pinna, as well as by 

 the distinct gonothecae. 



STATOPLEA. 



I have elsewhere* given reasons for modifying Professor 

 Allman's definitions of the genera Aglaophenia and Lytocarpus, 

 and need only mention here that the former genus is taken to 

 comprise all those species which combine the typical trophosome 

 of the Statoplea with a gonosome distinguished by the presence 

 of a corbula, open or closed, and variously modified, but always 

 composed of a number of ribs or leaflets (nematocladia) which 

 spring from a modified pinna ; while Lytocarpus consists of 

 species which have a similar trophosome, but in which the 

 gonangia are borne on separate nematocladia, each of which is 

 formed by the modification of a distinct pinna. 



It is generally considered, in accordance with the views of 

 Professor Allman, that the rachis of the Aglaophenian corbula is a 

 modified hydrocladium, and the ribs the modified mesial nemato- 

 phores of the hydrothecae which are sometimes present, but in 

 other cases are suppressed. Tt was formerly supposed that the 

 corbula was formed from a branch, and that the ribs were modified 

 pinnae, but to this view it was objected that the corbula took the 

 place of a pinna, and that the frequent presence of one or more 

 hydrothecse on the basal part of the rachis negatived the idea of 

 its being a branch. From the descriptions of P. setacea and P. 



*"The Genera of the Plumulariidae," &c. Trans. Royal Soc. of Vic- 

 toria, Vol. XXIII. (1887), page 83. 



