ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
70 
in the union of a bunch of polyps to form a colony, and in the eoenenchyme 
which binds them together, and forms the common stem by which their 
proximal portions are united. They are of interest as indicating how 
the steps by which skeletal structures, at first purely ectodermic, may, 
as a consequence of the great thickening and subsequent fusion of the 
mesogloea and continuous polyps, lose their primitive position, and became 
wholly included, as are the spicules of the majority of the Alcyonaria , 
in the mesogloea. The Helioport doe and Xeniidse appear to be derived 
from a common ancestor in which the skeleton was completely ectodermic. 
In the Helioporidae the differentiation has been effected by the speciali- 
sation of the endodermic canals and the extreme development of the cal- 
cigenous elements. In the Xeniidae, on the other hand, there has been 
a development of a thick mesogloeal eoenenchyme at the expense of the 
calcigenous elements, and a subordinate, but on the whole, well marked 
differentiation of the endodermic canals. Mr. Bourue points out how 
much the progressive development of the mesogloea in the Xeniidae, 
accompanied by intrusion of ectodermic elements, which were originally 
distinct from it, bears out the views as to the nature of the mesog’oea 
which he expressed ten years ago iu his paper on Fungia, 
Studies on Sea-Anemones.* — Dr. L. Faurot has endeavoured by 
elaborate histological and anatomical studies to throw some light on 
the relationships of Hexactiniae and other Actinozoa. The first part 
of his memoir is devoted to a general account of the anatomy of Sea- 
Anemones, which is naturally for the most part a summary of well-known 
facts. When he comes to the histology, however, he has some details to 
add to our knowledge of the mesoderm or mesogltea. A general account 
of development is then given. In Adamsia palliata, and Sagartia 
parasitica , total segmentation results in a solid morula, this becomes a 
planula, a circular depression at one pole forms mouth and gullet as the 
internal mass gradually diminishes, soon eight septa and eight tentacles 
make their appearance, aud thereafter the typical dozen are formed. 
M. Faurot discusses the development and disposition of the mesenteries 
in the various types of Actinozoa, and gives a clear diagrammatic 
summary of his results. 
The second part of the memoir contains a description of the structure 
and development of Edwardsia Beauxtempsi De Quatrefages, E. adenensis 
sp. n., Halcampa clirysanthellum Peach, Pvachia hastata Gosse, Elvactis 
Mazeli Andres, llyanthus purthmopeus Andres, Tealia crassicornis , 
Sagartia parasitica , Adamsia palliata , Palythoa arenacea and P. sulcata , 
Zoanthus Perii Audoin, Cerianthus membranaceus Gmelin, aud Arach- 
naclis, which the author has previously maintained to be only a larval 
Cerianthus. 
Arachnactis albida Sars.j — Dr. E. Vanhoflfen describes this rare 
Actinian, and publishes a- coloured sketch from life. The animal has 
hitherto been little known, except in its young stages or from poor 
specimens. In returning from Greenland, on the Danish brig 4 Con- 
stance,’ the author passed through a swarm, and captured a considerable 
number. Alcohol, picric acid, and corrosive sublimate are of little use 
* Arch. Zool. Exper., iii. (1895) pp. 43 262 (12 pis and 29 figs.). 
t Bibliotheca Zoologica (Leupk irt and Chun), lloft 20, 18J5, pp. 1-15 (1 pi.). 
