THE STRUCTURE AND AFFINITIES OF BUNOPS SCUTI- 
FRONS, Birge. 
By Harriet Bell Merrill, M. S., Instructor in Biology, Milwaukee 
High School. 
This paper describes a member of the family Macrothricidce 
found by Professor E. A. Birge at Minocqua, Wis., in Lake 
Kawaquesaga, July, 1892. It was recognized by him as the 
type of a new genus, and is described in this volume (pp. 
275-317) under the name of Bunops scutifrons. Numerous 
specimens, preserved in alcohol, were given to me 
with the request that I would study the anatomy 
as far as possible and determine the relationships of the genus 
to the other members of the family. The anatomy of the skele¬ 
ton and appendages was especially desired, as Dr. E. Daday 
de Dees in his Crustacea Cladocera Faunae FLungaricoe had de¬ 
scribed a closely allied species as belonging to the genus 
Macrothrix , under the name M. serricaudata. Herrick also had 
seen in Minnesota another member of the genus and described 
it as Macrothrix pauper . It was therefore necessary to study 
the appendages carefully with reference to the corresponding 
structures in Macrothrix and the other members of the family. 
In July, 1893, a very few specimens were found at Madison, 
and some notes were made on the internal organs, but lack of 
time prevented a complete study of the internal anatomy. 
DESCRIPTION. 
Viewed laterally the general form of the body is round, (PL 
XIV, Fig. 1). The height and length are nearly equal, the 
length usually exceeding the height. The dorsal margins of 
the valves are coalesced to form a strongly and evenly arched 
keel or crest extending the entire length of the body. At the 
posterior end, the crest forms a marked rounded projection 
ii—6 
