17 Ocel 
COELENTERATA. 
longer be considered either regularly radial or bilaterally symmetrical j 
they are either “ centripipodische,” or less frequently an “ amphitect 
pyramidale.*’ 
11. Heider, a. von. CeriantJius memhranaoeua fliiiime. Ein Beitrag zur 
Anatomie der Aotinien. SB, Ak. Wien, Ixxix. pt, 1, pp. 204-254, 
pis. i.-vi. 
The anatomy of this genus has been studied more elaborately by the 
Hertwigs (12). 
12. Hertwig, O. ^ R. Die Actinien, anatomisoh und histologisch mit 
besonderer Beriicksichtigung der Nervenmuskelsy stems untersucht. 
Jen. Z, Nat. xiii. Hefte 3 & 4, 220 pp., 10 pis. ; also published sepa- 
rately under the title “ Zur Blattertheorie,” Heft 1. 
The first chapter of the special part deals with the anatomy and 
histology of Sagartia parasitica^ Adamsia diaphana, Anthea cereus and 
cinerea^ Actinoloha diaphana^ Tealia crassicornis. In describing the 
ectoderm of the tentacles and peristome, the authors divide it into three 
layers, epithelial, nervous, and muscular. These three were previously 
described by Heider, who joined the muscular layer with the supporting 
lamella (Stiitzlamelle) to form the mesoderm. Heider found three kinds 
of cell in the epithelium, the nettle cells, gland cells, and “ glimmer ” 
cells, to which the authors add a fourth, the sense cells. The mesoderm, 
consisting of a supporting lamella alone, is situated between the mus- 
cular sheaths of the ectoderm and endoderm ; in Anthea and Sagartia 
it may be divided into an outer and inner layer. In the endoderm, the 
same layers may be found as in the ectoderm, with slight modifications. 
The presence of a distinct nervous layer in the endoderm of these 
forms is definitely established. The yellow globular bodies often found 
in the endoderm cells are said by the authors to be vegetable uni- 
cellular parasites similar to the “ yellow bodies ” of the Radiolaria. The 
second section of this chapter deals with the histology of the theca 
and foot, and the third section with that of the oesophagus. In the 
endoderm of the oesophagus there are two kinds of gland cells, some with 
little globules and ciliated, and others having a granular network, 
nucleated and without cilia. In treating of the anatomy of the septa, 
which occupies the next section, the structure of the generative organs, 
the mesenteric filaments, and the acontia is described. The ova arise from 
the endodermal epithelium cells lining the mesenteries, and, as they grow, 
become pushed into the substance of the supporting lamina which occu- 
pies the middle of the septum. The spermatozoa probably arise from the 
endoderm in a similar manner. The mesenteric filaments and acontia differ 
in their mode of attachment, and also in the fact that the former possess 
a greater number of gland cells than nettle cells, and the latter a greater 
number of nettle cells than gland cells. The second chapter deals with 
the anatomy and histology of Cerianthiis, Edward sia, and Zoanthus. 
The second part commences with the systematic position of the Cvelen- 
terata, discussing the relationships of the Actiniidce, Gerianthuhe, Zoan- 
thidccj and Edwardsue. The Zoanthuhe are probably the earliest type. 
They are provided with very numerous septa, and the arrangement and 
