IO NATURAL HISTORY BULLETIN. 



for the asexual multiplication of P. -pinnata as above des- 

 cribed. 1 It is the first recorded instance of the kind among 

 the Hydroida so far as I can find, although it bears consider- 

 able resemblance to the fissiparous formation of frustules as 

 recorded by Allman. 2 



Plumularia halecioides Alder. This minute Plumu- 

 larian was found parasitic on Antennularia. The gonosome 

 was not present. 



Plumularia alleni, 3 n. sp. 



Habitat. Found growing on Antennularia ramosa. This 

 delicate species bears considerable general resemblance in 

 size, form, and parasitic habit to P. halecioides. It differs, 

 however, in having a non-fascicled stem, smaller hydrotheca?, 

 more numerous nematophores, and especially in the gonangia, 

 which are greatly unlike the annulated structure oiP. halecioides. 



Aglaophenia pluma Linn. In studying the development 

 of the corbula? of this species, an interesting fact regarding 

 the sarcostyles was noticed. A young corbula was under 

 examination, the leaves or ribs of which had not yet coalesced, 

 and the sarcostyles of one leaf were seen to stretch across and 

 attach themselves to the next leaf in front, and remain for 

 some time in that position. It appeared as if these sarco- 

 styles served as temporary attachments to hold the edges of 

 the two leaves together, while they were connected by trab- 

 icula? of coenosarc, which rapidly formed a stronger and per- 

 manent connection. The perisarc of the edges of the leaves 

 seemed exceedingly thin, and in places appeared to be want- 

 ing. A contact having been established between the edges 

 of adjacent leaves, the permanent attachment was soon formed, 

 and the ccelomic cavities of the leaves established connections 

 at these points. A little later, currents of water bearing 

 granules were seen to flow in active streams from one leaf to 



1 See American Naturalist, November, 1895. 



8 Gymnoblastic Hydroids, p. 152. 



3 Named in honour of the Director of the Plymouth Laboratory, an 

 enthusiastic worker in marine zoology. Detailed description with figures 

 will be published in Ann. and Mag. Nat. Hist. 



