34 ARVID R. MOLANDER, ALCYONACEA. 
To this genus belongs only one northern species Alcyonium digitatum, but from 
their systematic interest, I must deal with some of its exotic species. 
Alcyonium glomeratum HASSAL. 
With the genus Gersemia MARENZ. KUKENTHAL (1906) classes Bellonella variabilis, 
which was described in 1901 by StupDER. Further on I shall show in greater detail the 
inaccuracy of the classification of Gersemia as a genus, after KUKENTHAL. GG. variabilis 
is undoubtedly an Alcyonium, even if the specimens described are not fully developed. 
When investigating young specimens of Alcyomium digitatum, my attention was called 
to the great external differences between the shape of the colonies and that of the fully 
developed. This quite naturally led me to suspect a similar condition of things in the 
case of other species too, and my supposition was confirmed on investigating Gersemia 
variabilis, which I found to be a not fully developed specimen of Alcyonium glomera- 
tum (HASSAL). 
On investigating STUDER's original specimens, I find as follows: 
From a short, broad, sterile base, a trunk arises, which soon divides into two 
large lobe-like branches. Even below the ramification, the trunk bear anthocodiae, 
which are spread evenly over the whole colony, and are all of the same kind. The lower 
part of the anthocodia consists, in most cases, of a calyx, 2—3 mm. in length, with longi- 
tudinal ridges, which end in papillae. This calyx is, however, completely retractile. In 
consequence of the strong armature it is often well developed. The origin of the papillae 
is that, on retraction, the spicules in the ridges of the calyx are pushed forward past the 
upper corner. 'The calyces present some likeness to a bird”s-nest, a feature which is 
also characteristic of A. glomeratum. The retractile part of the anthocodia contains 
eight double rows of spindles, which converge towards the top and are as much as 0,25 mm. 
in length, the spindles being scattered and having short thorns. Towards the shaft of 
the anthocodia, the spicules take on the shape of a transversal wreath, composed of 
some irregularly placed rods and spindles. In the calyx there are spindles and rods, 0,3 
mm. in length, besides double stars. In the inner coenenchym the spindles and rods 
are about 0,25 mm. in length. 
As regards the interior construction, this species shows a clear Alcyonium character. 
STUDER describes the canal system as follows: 
»Au-dessus vient une épaisse couche gélatineuse dans lagquelle sont disposés les 
sclérites. Elle contient de petites cellules granuleuses de formes irrégulieres qui pro- 
duisent de nombreux filament protoplasmiques se recontrant avec des filaments d”autres 
cellules et forment ainsi un réseau, qui unit les cellules ectodermiques aux cellules endo- 
dermiques, qui tapissent les tubes des polypes. Ce tissue est identique å celui de la cloche 
des meduses et représente un systéme de nutrition entre P'endoderme et I'ectoderme. Le 
méme tissue se trouve entre les tubes des polypes qui sont rapprochés du centre de la 
colonie, et lå ces cellules se groupent pour former de vrais filons qui se ramifient et vont 
d'un tube å Pautre; quelque fois ils entourent un canal trés mince et se transforment 
en tubes nutritifs capillaires.» 
