14 THE VOYAGE OF H.M.S. CHALLENGER. 
for it has its representative in the condition of the ordinary hydrocladia in the Eleuthero- 
plean genus Schizotricha 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 Cladocarpus pectiniferus (Pl. XVII.) the phylactocarp is a bifureating branch 
which springs from the proximal end of a hydrocladium, and supports the gonangia 
along its sides. It is destitute of hydrothece, 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 Cladocarpus 
Jormosus of the Challenger and ‘“ Porcupine” expeditions (Pl. XVI. figs. 4 and 5), and in 
Cladocarpus paradiseus, Cladocarpus dolichotheca, and Cladocarpus ventricosus, 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 Plumularide. In Cladocarpus pectiniferus (Pl. XVII. fig. 3), Clado- 
carpus formosus (Pl. XVI. fig. 5), and in some other species, the mesial nematophore of 
the hydrotheca, immediately behind which the phylactocarp 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 
hydrothece 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 hydrothece largely contribute. 
In Pleuwrocarpa 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 Bul. Mus. Comp. Zool., loc, cit., p. 136, pl. iii. fig. 2, 
ae tt 
