The Copepod Fauna of the “Maare”’ of the Eifel. 293 
XXXIX.—The Copepod Fauna of the “Maare” of the Eifel. 
By Dr. Jutius VossELer *. 
Since Leydig’s + investigations upon the fauna of the crater- 
lakes of the Hifel, the so-called “ Maare,” scarcely any natu- 
ralist has given any close attention to the lower animal world 
of those basins. Of the lower Crustacea only the Cladocera 
were investigated to some extent, while of the Copepoda only 
the occurrence of Cyclops in several lakes was mentioned. 
When in August of last year Dr. O. Zacharias | undertook 
the study of the microfauna of these waters, which are inter- 
esting in many ways, I took upon myself the task of working 
up the Copepoda, and the more willingly as in so doing 
valuable information upon the distribution of species, the 
adaptability of the group under consideration, and various other 
interesting questions was to be expected. 
As Dr. Zacharias was permitted to make his captures in 
part by means of a boat (on the Laacher See and Gemiinder 
Maar), and, further, the pelagic fauna was pursued also at 
night, the following catalogue may furnish, at least for that 
time of the year, a tolerably complete picture of the distribu- 
tion of the species and genera of Copepoda in the ‘* Maare.” 
The greatest number of species is harboured in the 
I, LAACHER SEE. 
By far the greater part of the Copepoda found here belong 
to the littoral fauna. Of Cyclopide the material placed at 
my disposal contained :— 
1. Cyclops viridis, Fischer ; 
2. 
3. 
tenuicornis, Claus; 
signatus, Koch ; 
and of these three large species Cyclops viridis was the most 
abundant. Most of the animals were adult, but ovisacs only 
occurred very rarely in the females. ‘he most numerously 
represented was 
* Translated from the ‘ Archiv fiir Naturgeschichte,’ Jahrg. 55, Bd. i. 
p. 117, Tafel vi. 
+ ‘Verhandl. Ver. d. preuss. Rheinlande und Westfalen, Jahrg, 37 
1881). 
¢ See his “ Bericht iiber eine zoolog. Exkursion an die Kraterseen der 
Eifel ” (Biol. Centrallb. Bd. ix. 1889), to which this paper forms a supple- 
ment. 
