ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
797 
squamata gives some results which he has himself already published. 
With regard to the statements that there is no trace of an oral lacunar 
ring, and that the radial lacunae are only apparent and due to the cells 
of the deep surface of the radial nerve-trunks M. Cuenot remarks that he 
has been able to find them. The difficulty of discovering them is due to 
the small size of the species examined, which has really the same 
organization as larger Ophiuroids. 
Variations of Pontaster tenuispinis.* — Prof. F. Jeffrey Bell, who 
has had the opportunity of examining a large number of specimens of 
this species, points out that there are considerable variations in the 
proportion of the length of the arm to the radius of the disc, and that 
it grows to a fairly large size. The superomarginal plates also vary 
considerably in size, the papularia are sometimes quite indistinct, and 
there are considerable individual differences in the disposition of the 
spines on the actinal surface and along the ambulacral groove. He 
concludes that one variety and two species that have been lately 
separated all belong to one variable form. 
Structure of Skeleton of Culcita.j — Hr. C. Hartlaub calls attention 
to the marked difference between the rows of brachial plates and the 
discoidal plates on the ventral surface of this curious Starfish, and points 
out their extremely regular arrangement. On the dorsal side he dis- 
tinguishes a central and a peripheral region, and describes the peculiar 
stellate plates which are at first in contact, and are afterwards connected 
with one another by special trabeculae. The region of the stellate plates 
does not, as in Nidorellia , directly touch the superomarginals, but is 
separated from it by a special row of large vertically disjDOsed plates. 
Dr. Hartlaub offers critical notes on the already described species, of 
which he also gives a synoptical key, with a review of their distribution. 
Ccelenterata. 
Histology of Ctenophora. J — Hr. P. Samassa undertook an inquiry 
into the histology of the Ctenophora with the special view of investi- 
gating the nervous system, the characters of which have been so 
differently described by various observers. The epithelium is seen at 
its simplest in Eucklora, where each cell is capable of producing the 
characteristic granules ; in Hormijpliora most parts of the body have a 
simple epithelium, but in the stomach and the glandular stripes there is 
a differentiation, as some of the cells are secretory and others interstitial. 
The highest stage of this differentiation is seen in Beroe and Cestus, 
where the connective-tissue character of the interstitial tissue is marked 
by its fibrous structure. The author believes that most of the various 
forms of cells which are seen in the Ctenophora are referable to 
various stages of gland-cells. The resemblance between the epithelium 
of Ctenophora and that of Turbellaria, especially Polyclads, is very 
striking. 
With regard to the otoliths all authors agree that they are formed 
by epithelial cells and expelled from them ; but in Beroe it is easy to 
* Proc. Zool. Soc. Lond , 1892, pp. 430-3 (1 pi.). 
t Notes Leyden Museum, xiv. (1892) pp. 65-118 (2 photo plates and 4 figs.). 
t Arch. f. Mikr. Anat., xl. (1892) pp. 157-243 (5 pis ). 
