298 Dr. J. Vosseler on the 



1. Cyclops tenuicornisj Glaus. 



2. agilis^ Koch. 



3. maarensis, sp. n. 



The Calanidee are represented by 



4. Diaptomus castor, Jurine. 



In my Inaugui'al Dissertation *, like most of my prede- 

 cessors, I identified D. castor^ Jur,, and D. ccendeus, Fisch. 

 Mr. A. Poppe, of Vegesack, had the kindness to call my 

 attention to my error and sent me examples of Dinptoiniis 

 castor from which I was able to convince myself that the 

 description in the above-mentioned memoir was founded upon 

 Diaptomus cwruleus, Fisch., the two species being sharply 

 distinguished from each other. 



In the Maar last investigated, the 



IV. PULVERMAAR, 



there were only the three species of Cyclops: — 



1. Cyclops tenuicorniSy Glaus. 



2. agilts, Koch. 



3. maarensiSj sp. n. 



Of the three genera of Gopepoda which, according to the 

 foregoing statements, occur in the " Maare," we find : — 



1. Cyclops J with six species. 



2. Cantkocamptus, with one species. 



3. Diaptomus, with three species. 



The singular mode of occurrence of Diaptom.us cceruleus and 

 D. castor merits special mention. The former occurs usually 

 in the larger accumulations of water. But hitherto I know 

 of no case in which it belongs, as in the great " Laacher 

 See," to the pelagic fauna, nay, so far as the Gopepoda are 

 concerned, forms this almost exclusively. Diaptomus castor 

 which, from accordant statements, rather belongs to the 

 smaller stagnant waters, ventures, however, in the " Holz- 



* "Die freilebenden Copepoden Wiirttembergs und angrenzender 

 Gegeiideu " (Jahresbefte d. Vereins fiir vaterl. Naturkmide iu Wiirttem- 

 berg, 188(3, p. 167). 



