290 
the proximal half of which is adnate, and others which are cylind- 
rical and. erect. The first - form of hydrothecae is represented in 
Cuspidella procumbens Kramp, and the second in such species as 
C. humilis and C. costata. The genus Zygophylax (Perisiphonia) 
which is provided with cylindrical nematothecae has given. its 
contingent of operculate forms in the two species, Z. operculata 
Jåderh.”) and Z. grandis Vanh.,”) for which I must propose a new 
genus Abietinella, and Oplorhiza parvula Allm.,”) in which we 
find stalked, globular nematothecae stands in a similar relation 
to ,,Campanularia" armata Pict & Bed.”) as the above new genus 
to the species of Zygophylax. The genus Lafoéina ”) which possesses 
a similar form of operculum ås Cuspidella and Oplorhiza only differs 
from the latter genus in the possession of very long vermiform 
nematothecae. The long slender, sometimes tubuliform hydrothecae 
of the genus Stegopoma leave no doubt as to the near connection 
of the latter genus with the Lafoéidae, and the different modes of 
growth of the different species show distinetly how little systematic 
signifieance we ought to ascribe to the colonial form. The oper- 
culum of this genus is very characteristic, consisting of two plaited 
membranes, fixed each in a curve, formed by the hydrothecal margin, 
and thus divided by two triangular hydrothecal teeth. When we 
find such an operculum in a number of species, presenting a different 
habit of growth, it is to my opinion more reasonable to think that 
they belong to the same natural genus, and that the different forms 
of growth have been produced by the influence of outer circum- 
stances, than to divide these species according to the different 
colonial form, and to suppose that the same form of operculum may 
have arisen independently more than once. The latter standpoint 
has been taken by Prof. Nuttingé&) who has described three new 
7) 26,. p. 376. 
