14 THE VOYAGE OF H.M.S. CHALLENGER. 



for it has its representative in tlio couditiou of the ordinary hydrocladia in the Eleuthero- 

 plean genus ScMzotricha of the present Report. 



In all the instances now described, the phylactocarps must, as we have seen, be 

 regarded as more or less modified hydrocladia. To those which remain for consideration 

 we must assign an entirely different significance, for we now find them to be variously 

 formed appendages, which though specially developed as in the former for the protection 

 of the gonangia, are superadded to the hydrocladia, which retain their normal form. 



In Ckidocarpus pectiniferus (PI. XVII.) the phylactocarp is a bifurcating branch 

 which springs from the proximal end of a hydroeladium, and supports the gonangia 

 along its sides. It is destitute of hydrothecse, and carries along its entire length a 

 double series of opposite nematophores, which have assumed the form of long, spine-like 

 processes, giving a pectinated character to the phylactocarpal branches. In CladocM'pux 

 formosus of the Challenger and " Porcupine " expeditions (PI. XVI. figs. 4 and 5), and in 

 Cladocarpus paradiseus, Cladoccopus dolicJiotheca, and Cladoearpus ventncosus, of the 

 Gulf Stream exploration, we find a branched phylactocarp essentially similar to that just 

 described. ^ 



The morphological significance of the phylactocarp in Cladocarpus is not so obvious 

 as in that of other Plumularidge. In Cladocarpus picctiniferus (PI. XVII. fig. 3), Clado- 

 carpus formosus (PI. XVI. fig. 5), and in some other species, the mesial nematophore of 

 the hydrotheca, immediately behind which the phylactocarjD springs, is entirely absent ; 

 and this fact, supported by the analogy afforded by other forms of phylactocarp, would 

 lead us to regard the phylactocarp here as representing in a greatly modified form the 

 mesial nematophore of the proximal hydrotheca — a view which is scarcely invalidated by 

 the fact that it springs from a point not absolutely in the mesial line of the internode. 



There are, however, other cases in which the mesial nematophore of the proximal 

 hydrothecae is still present, and then we may perhaps regard the phylactocarp as 

 representing the mesial nematophore of a hydrotheca which had been itself totally 

 suppressed — a view which is justified by the analogy of other forms of phylactocarp, to 

 the formation of which, as we have seen, the greatly modified mesial nematophores of 

 suppressed hydrothecse largely contribute. 



In Pleurocarpa ramosa, a remarkable Statoplean from St. Vincent, Mr. Fewkes 

 describes the phylactocarp as composed of a series of ribs which take the places of 

 hydrocladia near the proximal end of a branch, the hydrocladia towards its distal end 

 remaining in their normal condition.' Though no gonangia appear to have been present 

 in the specimen, there can be no doubt of the structure in question being a true phylacto- 

 carp ; and then I should regard the ribs as representing the phylactocarpal appendages in 

 Cladocarpus with the hydrocladia, which in this genus carry them suppressed. They are 

 described by Mr, Fewkes as carrying along their length long tubular nematophores, and, 



1 Bid. Mus. Comj). ZooL, loc. cif., p. 136, pi. iii. fig. 2. 



