Rev. T. Hincks on the History of the Ilydroida. 389 



nematophore of the existing Plumularia " the last traces of the 

 structure of its ancient representative, the Graptolite." 



In this case we must conceive of the remote ancestors of our 

 recent forms as obtaining their food altogether after the manner 

 of a Rhizopocl, by help of the pseudopodia, which still survive 

 to supplement the work of the polypite. This view, however, 

 though ably supported, can hardly claim at present to be more 

 than a happy conjecture. 



A word as to the terms employed in this department of 

 Hydroid morphology. With our present knowledge, nemato- 

 phore can scarcely be accounted an appropriate designation for 

 these singular appendages. The presence of thread-cells is 

 certainly not the most significant or distinctive character which 

 they exhibit ; and it would seem that it is not universal. As 

 we have already the terras hydrothecce and gonotliecai^ I should 

 propose to name them sarcothecce^ wdiile the offshoot from the 

 ectoderm, which they enclose^ may be appropriately called the 

 sarcostyle. 



II. New Species o/" Plumularia (P. cornu-copise, Hincks). 

 [Plate XXI. figs. 1-3.] 



I have lately obtained at Ilfracombe a new Plumulariaj 

 which exhibits some interesting points of structure. In the 

 form of the calycle, the jointing of the stem and branches, and 

 the general arrangement of the sarcothec^ (nematophores) it 

 resembles P. Catharina, Johnston ; but from this species it 

 differs notably in size and habit, in the form of the gonothecaB, 

 and in the alternate arrangement of the ramules. It is re- 

 markable, however, that while the pinna3 are usually alternate 

 and somewhat widely separated, one or two of the lowest pairs 

 are not unfrequently opposite, as in P. Catharina. Another 

 distinction between the two forms is to be found in the structure 

 of the sarcothecaj that occur one on each side of the calycle ; 

 in P. Catharina they are pedunculate, in the present species 

 sessile. Looking at the wdiole assemblage of differences and 

 points of resemblance, it seems not improbable that we may 

 have in P. cornu-copice a derivative from P. Catharina^ though 

 it is now a strongly marked and well-established form. 



Fam. Flumulariidse. 



Genus Plumulaeia, Lamarck (in part.). 



P. cornu-copice^ n. sp. 



Plumes distributed at intervals on the creeping stolon. 

 Stems recurved, regularly jointed ; a single internode between 

 those which bear the ramules. Pinnce generally alternate, 



