ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
385 
Protophyta. 
a. Schizophyceae. 
Symbiosis of Algae and Animals.* — Prof. A. Famintzin describes 
the symbiosis of Tintinnus inquilinus with a diatom belonging to the 
genus Clisetoceras , previously erroneously described as an Ectocarpus. The 
structures described as “yellow cells” he divides into two classes, one 
formed by Zooxanthella exiracapsularis, the other by Z. intracapsularis. 
He has studied the vegetable parasite on species of the genera Collozoum 
and Sphserozoum. 
Aquatic Vegetation in the Dark.f — Herr H. de Vries has investi- 
gated the fauna and flora of the dark places in the water supply system 
of Rotterdam. He finds the latter to consist almost entirely of enormous 
brown masses of Crenothrix Kunthiana , together with a few desmids and 
diatoms. These were accompanied by large quantities of fresh-water 
sponges, and of Dreyssena polymorpha and Cordylophora lacustris. 
Dicranochsete.J — Hr. G. Hieronymus describes in further detail this 
genus of Protococcaceae, distinguished by each cell putting out one, or 
less often, from two to four hyaline bristles, from 80 to 160 p in length, 
composed of gelatin. The bristles pierce the gelatinous envelope of the 
cell, which is often conspicuously striated in a radial direction when 
stained, and are usually branched. The contents of each cell divide 
ultimately into from eight to twenty-four zoospores, which escape by the 
lifting up of a portion of the cell-membrane as a kind of lid which is 
furnished with spiny protuberances. The chlorophore contains one or 
more pyrenoids, as well as starch-grains. Each zoospore contains a 
nucleus. 
Coscinodisce8e.§ — With the view of checking the undue multiplica- 
tion of the genera and species of diatoms, Dr. J. D. Cox has studied the 
various forms of Coscinodisceae, and proposes the following seven types, 
round which several hundred alleged species range themselves, viz. : — 
Actinocyclus Ehrenbergii , Coscinodiscus subtilis , C. radiolatus , G. lineatus , 
C. radiatus , C. centralis , and C. marginatus. The characters of these 
seven types are given, and the following observations added : — (1) The 
so-called pseudo-nodule of Actinocyclus is less important as a generic 
mark than the other characteristics which are identical with the fascicu- 
late Coscinodisci. (2) Colour is an untrustworthy mark of species. 
(3) The number of fascicles is no mark of species. (4) The so-called 
subulate spaces in Actinocyclus are not marks of distinction of species. 
(5) Considerable changes of form may occur without becoming the 
ground of new species. (6) Sparseness of alveoli is often misleading 
as to pattern of marking, and is not reliable as a specific distinction. 
(7) A striated margin is often apparently present or absent, as more or 
less of the bevelled marginal zone of the fasciculate forms is shown. 
(8) New species have often been based upon different valves of the 
* Mem. Acad. Sci. St. Pe'tersbourg, 1890. See Neptunia, i. (1891) p. 33. 
f ‘ Die Pflanzen u. Thiere in d. diinklen Raumen d. Rotterdamer Wasserleitung,’ 
Jena, 1890, 8vo, 73 pp. and 1 pi.. See Bot. Centralbl., xlv. (1891) p. 46. 
X Beitr. z. Biol. d. Pflanzen (Cohn), v. (18S0) pp. 351-72 (2 pis.). Of. this 
Journal, 1889, p. 101. § Proc. Amer. Soc. Micr., 1890, pp. 184-204 (2 pis.). 
