1897.] Some Manitoba Cladocera. 293 
The hard parts, exoskeletons, of crustacea contain varying 
intermixtures of calcite and phosphate of lime. 
The bryozoans have cases composed of a mixture of calcite 
and aragonite. 
The brachiopoda have shells composed of calcite and some 
phosphate of lime, the latter salt being almost limited to the 
shells of the inarticulate division of this class—lingula crania 
discina, ete. 
In the lamellibranchs there is found some variation in the 
composition of shells of different genera, in some the shells are 
- wholly aragonite, in oysters and scollops (Ostrea, Pecten) the 
shells are calcite, whereas in mussels Mytilus and Pinnas, the 
outer layer is calcite, the inner aragonite. 
SOME MANITOBA CLADOCERA, WITH DESCRIP- 
TION OF ONE NEW SPECIES.’ 
By L S. Ross. 
No record is to be found among the literature upon Ento- 
mostraca, of any systematic work done upon this interesting 
division of the Crustacea in Manitoba or any of the Provinces 
of Canada. The region is yet open to the student of the dis- 
- tribution of the group. A short stay in the Province of Mani- 
toba in June, 1895 was utilized by the author in making a few 
collections from the region about Portage la Prairie on the 
Canadian Pacific Rail Road fifty-five miles west of Winnepeg. 
Before leaving the province some vials of alcohol were left with 
a resident of the town to be filled with collections. A vial was 
received every second week from the time of the visit until 
cold weather, the latest being filled Oct. 21, 1895. One vial 
remained to be filled the following spring. 
Collections were taken by the author from the Assiniboin 
River, from a deep weedy slough which was once the channel 
of the Assiniboin River, from railroad ditches and from prairie 
1 Read before the Iowa Academy of Sciences, Dec. 1876. 
