90 ERNEST WAREEN. 



In the species Plumularia aglaophenoides Bale,Ba\e^ 

 describes the occuiTence of pinnules in the following terms : 



"Hydrocaulus polysiphonic, flexuous, pinnas alternate, dis- 

 tant, given off from each flexure of the stem, with two distinct 

 oblique joints near the base, and obscurely jointed for the rest 

 of their length, bearing hydrothecas as well as pinnules ; pin- 

 nules alternate, approximate, one on each internode of the 

 primary pinnae, both series borne towards the front and 

 supporting a hydrotheca on each internode/' 



According to the definition of the genus Plumularia as 

 given by Nutting,^ the pinnte are without accessory branches 

 of any kind ; and the only other genera to which the present 

 species could be referred are Poly plumularia G. 0. Sars 

 (modified by Nutting) and Schizotricha Allman (modified 

 by Nutting). Nutting defines Polyplumularia as possess- 

 ing pinnae furnished with a hydrothecate ramulus or pinnule 

 which springs from the first internode, and is more slender 

 than the pinna from which it grows; while in Schizotricha 

 the pinnaj bifurcate beyond the first internode at least in the 

 mature colony. 



In the present species the ramulus or pinnule springs not 

 from the first internode, but from the first hydrothecate inter- 

 node. The pinnule arises from the pinna by a short internode 

 bearing no structures and with transverse nodes, just as the 

 pinna itself arises from the main-stem. This condition is 

 shown in Allman's"'' figure of Schizotricha unifurcata 

 Allman. Consequently, the lower of the two branches is to 

 be regarded as the pinnule, and the upper as the distal 

 portion of the pinna, as in the case of the species being 

 described. 



It is not very clear that this production of pinnules forms 

 a very satisfactory basis for founding a genus. The present 

 species is transitional in this respect between Plumularia 



' Bale, W. M., loc. cit., p. 126. 



^ Nutting, C. C, ' American Hydroids. Part I : The Plumularidas,' 

 1900, pp. 54, 78, 83. 

 ^ Allman, G. J., loc. cit., pi. vii, fig. 2. 



