6 ARVID R. MOLANDER, ALCYONACEA. 
Structure of the colonies of Alcyonacea. 
Canal system. 
According to v. KocH (1887), STUDER (1887), and May (1899), the most, primitive 
family within Alcyonacee is the Haimeidae (WRIGTH) with the following diagnosis: Soli- 
tary polyps: stolons do not exist. KÖKENTHAL (1906) questions whether this family 
is to be considered as a fixed one. LACAZE DUTHIERS (1900) proves that Alcyonacae in the 
youthful stage, as solitary polyps, are often greater than the polyps, of Haimea-species, 
and he states that it has been by no means proved that the specimens which belong to 
this family have reached fully decisive development. In other respects the species be- 
longing to Haimeidae are very rare and unsufficiently described and species once de- 
scribed have not been found again. BRocH (1912) has proved that Haimea hyalina 
(Kor. and DAN.) is identical with Alcyonium digitatum var. norvegicum (KOR. and DAN.) 
KÖKENTHAL (1906) supposes that the species of Haimea are not fully developed Co- 
nularids, and I will suggest that, also within other families, stolons do not always exist 
(compare BRocH, LACAZE DUTHIERS!). As it seems to me, it is scarcely probable that 
Haimeidae should be considered as a fixed family. Whatis mentioned above will show 
my reason for not including the fam. Haimeidae (WRIGTH) in my systematical treat- 
ment of Alcyonacea. 
The formation of colonies within Alcyonacea proceeds from a single polyp; 
from this, by means of budding, new polyps are subsequently produced, which, in larger 
or smaller numbers, constitute the colony. The simplest forms are to be found amongst 
the family of Cornulariidae DANA and especially in the genus Cornularia LAMARCK. In 
this genus, a few free polyps proceed from a narrow, creeping, horizontal tube, a stolon as 
it is called. This contains a simple cavity, which connects the basal parts of the polyps 
directly with each other. The walls of this simple stolon consist of thin ectodermal and 
endodermal layers of cells, between which there exists a mesenchymatic substance (= 
mesogloea) (Fig. 1). In the case of Cornularia, the stolons, as a rule, preserve a tubular form, 
but sometimes become creased or flattened. On continued development, as, for instance, 
in the case of certain species of Clavularia, the stolons take on a more tape-like form, 
and at the same time the mesogloea attains more marked development, and the primary 
cavity in the stolons is divided into a number of shorter endodermal canals and strings, 
or rows of cells (Fig. 2). The canals combine freery with each other by anastomosis of 
