354 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
families : the Cornulari[i]dae, in which the polyps are connected with 
one another by stolons or stolon-plates, and are all of much the same 
length when fully developed ; in the other families — the Alcyoni[i]dse 
and the Scleraxonidas, the polyps are connected with one another by 
branched tubes, which rise to various heights, and have their walls fused 
into a common mass. The polyps may be very unequal in length. In 
the Alcyoniidae the spicules are separated from one another, while in the 
Scleraxonidae they are united into continuous skeletons, either by horny 
substance or by crystalline calcareous excretions. 
Cornularia , Clavularia , and Bhizomenia are the recognized genera of 
the Cornulariidae ; Alcyonium , Daniela, Cercopsis, and Pciralcyonium , of 
the Alcyoniidae, and Corallium of the Scleraxonidae. 
Clavularia Marioni is a new species ; Daniela Koreni, new genus and 
species, and Cercopsis Studeri is a new species. 
Fissiparity in Alcyonaria.* — Prof. T. Studer calls attention to an 
Alcyonarian allied to Gersemia , and collected by the Prince of Monaco, 
which shows that fission does occasionally occur among the Alcyonaria. 
The specimen, unfortunately, is unique, and the author has had to con- 
tent himself with a superficial examination. 
Development of Arachnactis and Morphology of Cerianthidae.t — 
Prof. E. van Beneden reminds us that Kowalevsky has shown that the 
endoderm of Cerianthus is formed by invagination, and that this 
Anthozoon passes through the gastrula-stage. The pharyngeal tube is 
formed by the pressing back of that part of the wall of the body which 
immediately surrounds the wall of the gastrula. This is effected in such 
a way that two endodermic caeca are formed, one on either side of the 
pharyngeal tube. This latter is flattened and has two surfaces and two 
edges ; the former correspond to the caeca, while the edges are united 
to the wall of the body. Each caecum soon divides, by the formation of 
a partition which unites the w all of the body to the lateral surface of the 
pharynx, into two chambers. At this time the first two pairs of tentacles 
have appeared, and they correspond to the first four mesenteric chambers. 
These results cannot be reconciled with those of Boveri, who makes no 
mention of Kowalevsky’s results ; in this Prof, van Beneden thinks he 
has erred, as his own studies of Arachnactis w’ill show. The present 
observations made on Arachnactis albida demonstrate that, at the stage 
of development wLich is characterized by the presence of two pairs of 
tentacles, there are no signs of median chambers ; the larvas have, at the 
level of the pharynx, two cavities divided into four symmetrical mesenteric 
chambers. The appearance of these cavities is probably the consequence 
of the mode of formation of the pharynx and the primitive form of this 
organ. The pharynx forms a complete partition which separates the 
right from the left cavity. In the Hexactinaria and Hexacoralla it is 
different — in them the pharynx from the first occupies the axis of the 
ovoid larva ; their pharynx does not divide the coelenteric cavity into 
two lateral parts, and that cavity is undivided. 
The first pair of mesenteric septa are transverse in Arachnactis , and 
to the mesenteric cavities there correspond the first two pairs of marginal 
* Bull. Soc. Zool. France, xvi. (1891) pp. 28-30. 
t Bull. Acad. Roy. de Belgique, lxi. (1891) pp. 179-214 (4 pis.). 
