ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
69 
Crinoids in the possession of “ false pinnules,” that is to say structures 
apparently resembling pinnules but springing from the middle, of the 
sides of the brachials, not from their distal angles, and often being one 
on each side of a single brachial. So inexplicable is this arrangement 
that, in another part of this very paper, the author stigmatizes it as “ an 
evolutionary impossibility.” Not the least valuable part of this mono- 
graph are the very beautiful drawings by Mr. G. Liljevall, which are 
superior to all illustrations of fossil Crinoids that we have ever seen. 
Coelentera. 
Development of Pelagia.* — Prof. A. Goette finds that the alleged 
contrast between Pelagia and Aurelia , as regards development, does not 
exist. The larva of Pelagia noctiluca falls short of a Scyphostoma only 
in the absence of tentacles and funnel- muscle : the whole internal struc- 
ture is that of a reduced Scyphostoma. One may regard Aurelia, 
Cotylorhiza , and Pelagia as three stages in the reduction of the Antlio- 
zoon-like ancestral form of the Scyphomedusae. 
Reappearance of Limnocodium Sowerbii.f — Prof. E. Ray Lankester 
makes the appearance of this freshwater Medusa in the Sheffield Botanic 
Gardens the text for an interesting note of what is certainly known as to 
its history, and points out that we have still to learn how the polyps 
which give rise to the Medusae themselves originate. 
Porifera. 
Studies on Spongillidae4 — Dr. W. Weltner begins with a description 
of the structure of the gemmulae as observed by himself and by others. 
The shell consists of several layers : — (1) an internal chitinous cuticle 
with a pore, or pore-tube, or several pores, closed during winter ; (2) an 
air-containing layer, probably hydrostatic, and containing the character- 
istic spicules ; and in some cases (3) an external cuticle. The germ 
within consists of numerous closely packed uniform cells, whose plasma 
contains many refractive yolk-granules. In each cell there is at first 
a single nucleus, but in many cases two or more appear, perhaps by 
direct nuclear division. The changes within the germ before it emerges 
from the cell, and its behaviour in liberating itself are then discussed. 
The green gemmules of Eusjpongilla lacustris are described in detail. 
The zoochlorellse are associated with some plasma in addition to the 
chlorophyll, and they are absent from some cells of the gemmule as 
from some cells of the adult. As to the brown pigment of Spongilla 
fragilis, Weltner notes that it is apparently affected by light, and lies 
in granules in some of the internal cells of the sponge. When this 
sponge shows green colouring, as it sometimes does, zoochlorellae are 
present. The brown granules are absent in sponges living under 
stones, and are probably closely allied to the brown pigment of Hydra 
fusca. 
Weltner then gives the results of a number of experiments pn the 
influence of cold on the gemmules. Many are not killed after regaining 
* SB. K. Preuss. Akad. d. Wiss., 1892, pp. 853-61. 
t Nature, xlix. (1893) pp. 127-8. 
x Arch. f. Naturgescli., lix. (1893) pp. 245-84 (2 pis.). 
