KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 51. N:o |l. 9 
vigorously provided with spicules, the cell-strings only occur.' The cell-strings occur 
in the most delicate tissues, for instance, in the septae and in the mesenterial filaments. 
The canals appear to be secondary formations, which have originated in the cell-strings. 
The canals and the cell-strings convey the nutriment. The endodermal cells of 
their walls possibly have a digestive or secretary functions (PRATT 1902, 1905). These 
cells also may be amoeboid, as PRATT has found with Alcyonium digitatum. 
If we examine the numerous membranous forms within fam. Alcyomidae and 
Nephthyidae, the connection between the horizontal and vertical canal systems appears 
with considerable clearness. In the case of a large number of Alcyonium-species, for 
instance Å. membranaceum KUKENTHAL, Å. reptans KUKENTHAL, Å. contortum KUKEN- 
THAL, Å. digitatum (L.) var. norvegicum (KOR. a. DAN.), and further Gersemia? fruticosa 
(SARS) forma membranea (= Sympodium hyalinum GRIEG), there appear at the base 
of the colonies more or less numerous horizontal canals and strings, of which the former 
extend very considerably where the polyps are scattered on the membrane. Where the 
polyps, however, are forced together and the number of polyps increases through a more 
Fig. 6. Diagrammatic vertical section through a colony of a membranous ÅAlcyonium. 
p = polyp, c = canals. 
intense budding (Fig. 6), the solenia mostly consists of vertical canals and strings. The 
vertical net has, however, not yet reached its full development in most cases, but the 
small cell-strings creep nearly along the coelenterons. The horizontal, basal canals are 
well developed, however, and they constitute the most important system of communi- 
cation (PI. III fig. 35). Sometimes a direct connection occurs between the basal parts 
of the coelenterons (P1. III fig. 31) above the horizontal, lateral cell-strings. Near the 
circumference of the membranous colonies, the basal canals sometimes develope into tubes, 
which often attain a considerable width, and, for a short distance, coalesce into large 
cavities (Pl. III, fig. 34, 36). 
As regards the development of the canal system, there are pronounced differences 
between the fam. Xenwidae and the Cornulariidae. In the former, the coenenchym is 
strongly developed, a trunk has been formed, and the solenia has, simultaneously, extend- 
ed in the coenenchym between the coelenterons, in the form of a vertically-placed net- 
work of more or less developed short, endodermal canals or cell-strings. The canals and 
cell-strings connect the coelenterons of the polyps indirectly with each other. As, in 
general, the development of spicules within species belonging to this family is compa- 
1 Beside the horizontal direct canals. 
> I have divided the genus Eunephthya sensu KÖKENTHAL into two genera Gersemia (= Eunephthyae 
alcyoniformes KÖKENTHAL) and Eunephthya (= Eunephthyae nephthyiformes KÖKENTHAL). 
K. Sv. Vet. Akad. Handl. Band 51. N:o 11. 2 
