Marshall—A Parasitic Osiracod. 
119 
which the parasites were less numerous. The probable means 
of infection, other than during copulation, seems to me to be 
as follows. In the daytime crayfish are found quite abun¬ 
dantly under the stones and logs in the streams and near the 
shores of the lakes. They leave these retired places to feed and 
then return to the same or similar localities. Here the para¬ 
sites could leave their hosts, the light being naturally excluded, 
and reach other crayfish which camie under the same stone. 
Lacking some of the larger systematic works, I have been un¬ 
able to definitely determine the position of Entocythere in the 
family Cytheridae to which it belongs. Muller’s (8) work 
gives but two genera of this family, to neither of which does our 
species belong. From Linnicythere it differs in having six ter¬ 
minal setae on the first antenna instead of two; in having the 
flabellum of the second antenna unsegmented, besides a marked 
difference in the structure of the maxilla. The maxilla is also 
quite different from 1 that of the other genus, Metacypris; be¬ 
sides the number of terminal setae on the first antenna, and the 
segments of the mandibular palp not being the sam)e. 
In the key given in Bronn’s (2) it is nearest to Loxochonca, 
differing, however, from a species of the same genus figured by 
Brady and Forman (1), in the form*, both of the posterior part 
of the abdomen and of the maxilla. It is alsoi very similar to 
Sclerochilus contortus Sars, as figured by Kaufman (7), but 
differs in the number of segments of both the second antenna 
and the mandibular palp, as well as in the general appearance 
of the maxilla. 
A reference to> the systematic table given in Bronn’s (2) or 
to those given by Sars (13) or Kaufmann (7) shows that Ento¬ 
cythere comes nearest to Loxochonca, but is enough different to 
claim a new genus. 
Methods : After their removal from the crayfish the speci¬ 
mens were killed in hot water, or in a mixture of equal parts of 
hot water and sublimate. Picro-sulphuric was also used but 
not considered as effective as either of the other methods. The 
specimens killed in hot water were either brought directly into 
alcohol, or, after their removal from) the water were first 
allowed to remain for fifteen minutes in a nearly saturated so- 
