560 Wisconsin Academy of Sciences, Arts, and Letters . 
Order BDELLOIDEA 
Adineta gracilis Janson. 
Adineta vaga Davis. 
Philodina citrina Ehrenberg. 
Philodina megalotrocha Ehrenberg. 
Philodina plena (Bryce). 
Philodina roseola Ehrenberg. 
Philodina vorax (Janson). 
Rotaria citrina (Ehrenberg) = Rotifer citrinus Ehrenberg. 
Rotaria macroceros (Gosse) == Rotifer macroceros Gosse. 
Rotaria macrura (Ehrenberg) = Rotifer macrurus Ehrenberg. 
Rotaria neptunia (Ehrenberg) =Actinurus neptunius Ehrenberg. 
Rotaria rotatoria (Pallas) = Rotifer vulgaris Schrank. 
Rotaria sordida (Western) =Callidina sordida Western. 
Rotaria tardigrada (Ehrenberg) = Rotifer tardus Ehrenberg. 
Machrotrachela habita (Bryce) = Callidina habita Bryce. 
Macrotrachela multispinosa Thompson. 
Macrotrachela nana (Bryce) = Callidina nana Bryce. 
Macrotrachela plicata (Bryce) — Callidina plicata Bryce. 
Macrotrachela quadricornifera Milne. 
Macrotrachela zickendrahti (Richters) = Callidina zickendrahti Richters. 
Dissotrocha aculeata (Ehrenberg). 
Dissotrocha macrostyla (Ehrenberg). 
Mniobia russeola (Zelinka). 
Habrotrocha augusticollis (Murray). 
Harbrotrocha constricta (Dujardin). 
Habrotrocha lata (Bryce). 
Habrotrocha munda Bryce. 
Scepanotrocha rubra Bryce. 
A Review of the Central Group of Notommatids 
One of the most difficult tasks connected with this survey proved 
to be the specific determination of the Notommatids, and as a first 
step towards a revision we undertook a re-examination of the 
central group of genera, as far as material was obtainable. Our 
original intention was to include all the Notommatids and to pub¬ 
lish the results in this paper. We were aware that this was quite 
a task, and when the war interrupted scientific work and inter¬ 
course it became necessary to restrict it to what has usually 
been considered the central group. Even so we have been unable 
to include the Proales-Pleurotrocha assemblage, not having access 
to essential material, and only a few species have been described 
without any attempt at determining their systematic position. 
