30 ARVID R. MOLANDER, ALCYONACEA. 
Xenia LAMARCK 1866. 
Diagnosis: Sterile, simple or ramified trunk, and thence appearing with a sharply 
depressed polyp-bearing end plate. 
1902 Xenia KÖKENTHAL. 
Subgen. Ceratocaulon (JUNGERSEN, 1891) KÖKENTHAL 1906. 
Diagnosis: The trunk with outer, ectodermal horny skeleton, in addition to the 
inner mesodermal. Unimportant coenenchym, and few, large, nonretractile polyps. 
NXenia wandeli (JUNGERSEN), 1891. 
Diagnosis: Spicules few, tentacles with two rows of pinnulae, at least twenty 
pairs in each row. 
1906 a, Xema wandeli KÖKENTHAL. 
This specimen is of very great interest, as being the only northern representative 
of the fam. Xeniidae. JUNGERSEN, when describing it, established a new gen. Cerato- 
caulon, which he classed close to Xema. KÖKENTHAL demonstrates (1906) the relation- 
ship between this specimen and Xema, but at the same time he shows its primitive cha- 
racter, and classes it together with Xenia antarctica, with the subgen. Ceratocaulon, which 
must, then, denote Xeniae of primitive character. 
As regards the structure of the anthocodiae and the colony, I refer to JUNGERSEN 
(1891). The walls between the coelenterons are poor in coenenchym, and there have been 
developed endodermal, almost entirely connected plates, without any canals. JUNGER- 
SEN states that, in the lowest part of the trunk, where the inner coenenchym is more 
developed, there exists a capillary net of endodermal cell-strings. There is, consequently, 
no other connection between coelenterons. That mentioned, however, could not be de- 
termined with complete certainty, on account of the lower parts of the specimen having 
been destroyed. The endodermal layer occupies the same position as the endodermal 
canal system, in other Xeniae for instance, and as, lower down, it resolves itself into a 
system of narrow camnals, we can assume that this endodermal layer is homologous with 
the endodermal, indirect canal system in the other Xeniae. Tt may be suggested that it 
is composed of endodermal cell-strings. As regards Xenia antarctica KUKENTHAL (1906a , 
p. 21) states that the coenenchym between the coelenterons is very insignificantly 
developed, and the canal system in this consists of thin layer of endodermal cell strings 
or row of cells. No direct connection between the gastral tubes exists, which, again, deno- 
tes that at least an indirect one exists, and that the endodermal layer and the capillary 
net lower down in the colony possibly performs its functions. 
The armament is weak, the spicules small, from about 0,05—0,29 mm., flat, but 
on one side somewhat arched, with few thorns. In shape they are broadly rectangular, 
lamellar, with an impression in the middle. 
