IOWA ACADEMY OP SCIENCES. 
159 
A specimen of S. vetnlus identified by G. O. Sars of Norway, 
and examined by the author, has the lower margin of the head 
straight to the very short beak, and the eye situated at a dis- 
tance from the lower margin, equal to about one-half the diam- 
eter of the eye. 
Herrick says in his description that the curved spines pres- 
ent in the other species at the caudo- ventral angle of the shell 
are absent from S. daphnoides. If this be constant it seems to 
be the only character not possessed by S. vetulus. 
The specimens taken in Manitoba, and also in Iowa, vary in 
size and shape of the head and of the body, — there are such 
grades of variation, and authors figure such differences of form 
in S. vetulus that it seems very probable that S. daphnoides is 
merely an extreme form of S. vetulus. 
Bosmina longirostris . — Found in only two collections: one from 
Lake Manitoba and the other from a slough at Portage la 
Prairie. 
Macrotlirix laticornis . — This species was met with only in a 
shallow prairie slough, and was by no means abundant. 
Bunops scutifrons . — This beautiful species was found rather 
frequent in the shallow prairie slough at Portage la Prairie. 
lliocryptus sp ? — A few shells and one individual of this genus 
were taken from the Assiniboin river. The species is probably 
longiremis, Sars. 
Alona quadrangular is; Alona costata. — There is some ques- 
tion as to the identification of these two species. Only a single 
individual of each was found. The specimen that may be Alona 
costata is not strongly striated, but other characteristics agree 
with descriptions of this species. 
Graptoleberis testudinaria var. inermis . — Although taken at 
three different places this species was rare. A few individuals 
were found in Rat creek, one in the collection from the Assin- 
iboin river, and one individual, and a few shells from a prairie 
slough. 
Dunlievedia setiger . — This species is apparently rare during 
the season of the year the collections were taken, as few indi- 
viduals were found. They were taken from a prairie slough. 
Birge, in‘ his “List of Crustacea Cladocera from Madison, 
Wisconsin,” mentions the fact of D. setiger being one of the 
rarest of Cladocera in that region, but that in the month of 
August he found them in immense numbers, both males and 
females. 
