with Observations on Australian Hydroids. 95 



Were it not that the " Challenger" specimens have been 

 identified by Mr. Busk and Professor Allman from actual 

 comparison with the original types of P. effusa, it would be 

 difficult to believe them the same. The figure in the 

 " Report" represents a strong, coarsely-growing species, with 

 very distinct pinnae, and calycles conspicuous to the naked 

 eye, as in the larger Aglaophenice ; while Kirchenpauer's 

 figure of P. effusa shows a slender form, in which not only 

 are the hydrothecse far too small to be seen without optical 

 aid, but the hydrocladia themselves are so delicate as to be 

 scarcely noticeable, like a fringe of very fine hairs. That 

 this is the more correct representation is proved by a sketch 

 of Mr. Busk's of a portion of the polypidom, which is 

 precisely like Kirchenpauer's figure, except that the pinnae 

 are a fraction longer. The magnified figure in the " Report" 

 also differs somewhat from that of Kirchenpauer, and from 

 Mr. Busk's sketches, notably in the hydrothec^e being less 

 ventricose, and in the direction of the folds in the hydro- 

 thecal internode. The nematophores are shown by Kirchen- 

 pauer as having the margin entire, while in the " Challenger" 

 figure it appears sinuated or canaliculate. Here the in- 

 accuracy is doubtless on Kirchenpauer's part, as all the 

 allied species have canaliculate sarcothecse ; indeed, I have 

 never met with an Eleutheroplean in which j'the struc- 

 ture was otherwise. 



Plumulaeia cornuta, Bale. 



This species might with propriety be placed in the genus 

 Polyplumaria, which, as now modified, is distinguished by 

 the presence of an accessory hydrocladium springing from 

 the proximal part of each pinna, although in P. cornuta the 

 accessory ramulus bears only a single hydrotheca, above 

 which it terminates in a blunt point. 



Plumularia Wattsii, n. sp. 



Hydrocaulus monosiphonic, branched, attaining a height 

 of about ten inches; stem very slender, almost equal in 

 thickness throughout ; branches numerous, small, disposed 

 around the stem in an irregular spiral, about 1-1 6th of an 

 inch apart, one on each stem-internode, close to the summit ; 

 sometimes bearing one or two small secondary branchlets as 

 well as the pinnae ; pinn^ short, alternate, one borne close 

 to the summit of each internode of the branches, divided 



