ADDENDA. 
See Text, Page 32. 
Plumularia geminata. 
Between the present species and the Pluwnularia catharina Johnston there 
is a close relation. The form of the hydrotheca, of the gonangia with 
their basal nematophores, and of the internodes in the ultimate ramuli, is 
very similar in the two species, while between the same parts in Plumu- 
laria catharina and Monostechas dichotoma (see p. 37) a corresponding identity 
of form will be found. 
FoorT-NoTE To PAGE 49. 
Iam indebted to Miss Gatty for an opportunity of examining a second species of the same remarkable 
form, which may well constitute a subgenus of Aglaophenia. From Aglaophenia perpusilla this differs 
chiefly in the width of the keel which runs down the front of the hydrotheca, and in the presence of a 
shallow constriction between that portion of the hydrotheca which lies at the proximal side of the: 
strong intrathecal ridge and that which lies at the distal side. A decided bithalamic character is 
thus given to the hydrotheca. The specimens scarcely surpass A. perpusilla in size. They are from 
the Gulf of Mexico, are attached to Gulf Weed, and are destitute of gonosome. I have assigned to 
the species the name of A. late-carinata. 
