44 THE VOYAGE OF H.M.S. CHALLENGER. 
anterior fold in its walls confers on the hydrotheca an aspeet which, though not confined 
to the present species, is by no means common, Besides its terminal orifice, the mesial 
nematophore is provided with a very distinct lateral orifice, close to the point at which 
it ceases to be adnate to the hydrotheca. 
In the specimen from which the drawings in the plate had been made, no gonangia 
were developed on the phylactocarps. The collection, however, contains another specimen 
in which they are present, and here they were always found singly on the inter- 
Fic. 2.—Phylactocarp of Lytocarpus spectadilis. 
a. Proximal internode carrying a hydrotheca. 
b. Second internode carrying a gonangium. 
c. Representative of the mesial nematophore of this internode. 
d. Representative of lateral nematophore, 
e. Continuation of the phylactocarp beyond the gonangium,-hearing internode. 
J, f. Representatives of the lateral nematophores belonging to the internodes of this continuation, 
g. Gonangium. 
h. Gonophore. 
node which immediately succeeded the proximal or hydrotheca-bearing internode of the 
rachis. The phylactocarps which thus carried gonangia had also undergone a peculiar 
modification, which consisted partly in an enlargement both in length and width of 
the gonangium-bearing internode, the solitary gonangium being borne by a rounded 
prominence which lay between the two lateral spines of the internode, while in 
this internode there also existed a small mesial spine, by which the gonangium was sub- 
tended, and which did not exist in the others, Further, the whole of the more 
