36 ARVID R. MOLANDER, ALCYONACEA. 
WRIGHT and STUDER, as well as by KÖKENTHAL, has been considered to be identical 
with G. bocaget (see Pl. IT fig. 22). 
KUKENTHAL classifies these species with Gersemia (sensu KUKENTHAL). The antho- 
codiae are totally retractile. STUDER hints at the possibility of Nidalia atlantica being 
related to Funephthya.: "The specimen which I have investigated is comparatively well 
developed, and has signs of lobe formation on the polyp-bearing part, which, without 
a dividing line, passes into the sterile, vigorous lower part. The spicules may be as 
much as I mm. in length, very vigorous, sparsely distributed spindles and rods. 
On a closer comparison between Nidalia atlantica and a large number of Gersemia 
and HPunephthya species (sensu MOLANDER), besides Alcyonium species, I come to the 
conclusion that the relationship accepted by STUDER is wrong. TI base this conclusion 
of mine, first of all, on the distinct Alcyomium-character of the spicules, although they are 
unusually large and powerful. This applies equally to the spicules of the anthocodia 
and to those of the branches. Further, the specimen examined did not show the least 
sign of ramification, although it was fairly well developed. On the other hand, a sign 
of division of the polyp-bearing part into two parts (lobes) could be observed. The lower, 
sterile part of the colony passes, without a definite line of division, into the upper part. 
This mode of growth is found more frequently in the case of Alcyomium. In this genus 
a young, or a not fully developed specimen often assumes an abnormal shape, as we saw 
just now in the case of Alcyomum glomeratum. In Gersemia or Eunephthya specimens 
(sensu MOLANDER) the branches may be wanting, but, in such cases, the colony as- 
sumes quite a different form; a trunk is obvious, and the situation of the polyps 
becomes altogether different. "The geographical distribution does not correspond with 
that of Gersemia and Hunephthya (sensu MOLANDER). I had not the opportunity of 
investigating the canal system of Nidalia atlantica. On account of the shape of the 
spicules and the colony, I place Nidalia atlantica (= Gersemia bocagei sensu KUKENTHAL) 
with Alcyonium. 
Aleyonium digitatum LINNÉ, 1758. 
Diagnosis: The bark of the upper part of the colony has short rollers with girdles 
(dumb-bells) and crosses, 0,,—0,2 mm. in length. In the inner coenenchym the spicules 
rather pass over into irregular crosses, or spindles and rods, with large processes. 
1894, Alcyonium digitatum HIcCKSoN. 
Alcyomium digitatum was already known to LINNÉ and has been described in more 
or less detail by a great number of writers. Tt is one of the most common ÅAlcyonaceae 
in the boreal fauna of the northern seas. Beside this species, there is described a variety 
Alcyonium digitatum var. norvegicum (Kor. and DAN.). Originally the latter was 
described as a Sympodium, but KÖKENTHAL (1906) accepted is as an Erythropodium, a 
description which was confirmed by BrRocH 1912, who, in addition, distinguishes it as a 
separate species. 
!' STUDER retains the classification of KUKENTHAL, 1896, 
