Harring and Myers—The Rotifers of Wisconsin. 561 
What was supposed to be a fairly homogeneous group turns out 
to be quite otherwise upon closer examination, as is frequently 
the case. There remains consequently but a somewhat haphazard 
aggregation of Notommatids. But even so, we feel that it will 
still be useful to publish the descriptions and figures here 
presented, as the existing information on this group is so scanty 
and largely antiquated. It is our hope to take up the remainder 
of the group in a subsequent paper, which will also deal more 
fully, with the taxonomy. We have refrained from any but the 
most obviously necessary generic rearrangements; the greater the 
number of species studied, the more impressive becomes the fact 
that the species of such a very old and, in its larger features at 
least, relatively homogeneous group, have in their development 
followed a great many and diverse crossways and byways, and the 
unraveling of these is a very difficult task, which certainly ought 
not to be attempted without the fullest possible knowledge of all 
the available species. 
Special efforts have been made to give characteristic figures of 
the trophi, as it developed that no two species are identical in this 
respect, and since determination of species is possible from the 
trophi alone, which is very fortunate in view of the difficulties 
of preservation. A word of caution concerning the use of the 
figures is necessary; the sclerified parts of the Notommatid mastax 
are generally extremely complicated, and an exhaustive study, 
such as that made by Zelinka of Synchaeta atlantica, would have 
consumed more time than we could command. We have there¬ 
fore figured as faithfully as possible the salient features. Many 
minor details in the internal ribbing and bracing provided in the 
rami to resist or to transmit the stresses of the muscles have thus 
been omitted, but we hope that enough has been given to serve 
the purpose of identification, which has been our principal aim, 
and that it may also be of assistance in disentangling the inter¬ 
relations of genera. 
36—S. A. L. 
