EUCOPEPODA FROM TANGANYIKA. 823 
probably constant for a given species, we are furnished with an 
explanation of the otherwise perplexing fact that this lateral 
torsion may be either to right or left. It will be the one or the 
other according to the particular side of the host which formed 
the point of attachment for the parasite. Quidor, moreover, 
gives evidence for believing that the amount of torsion is constant 
for a given species, and can be used as a character of systematic 
value. 
The appendages appear to show comparatively minor differences 
within the limits of this genus, and have not been appealed to 
for the purpose of establishing new species. Thus I have not 
deemed it necessary to study in detail the head appendages of 
my new forms, since these are by no means easy to investigate, 
and my material, with one exception, was very seanty. So far 
as I have been able to make out, there are no points of striking 
_ difference in any of the types from the arrangement which is 
usual in the group. Accordingly in the specific descriptions 
which follow, no special mention of head appendages, Swimming- 
feet or furcal appendages is made, it being implied that these 
are present in the normal manner, without baving any bearing 
on the distinctions between the species. 
Tn addition to the photographs reproduced in the plate, the 
accompanying text-figure is given, showing in outline for the 
three new species the appearance of the head and cephalic arms 
from above. 
Text-figure |. 
Diagram showing cephalic arms, as viewed from above. 
A. Lern@ocera diceracephala. LB. L. haplocephala. C. L. temnocephala. 
In order to facilitate identification, and in order to emphasise 
in very concrete form the chief features which characterise the 
new species, a key to all the known species of Lerneocera has 
been prepared. This did not prove a very casy task, as unfortu- 
nately it has been possible for me to examine specimens of only 
two of the forms which have been described. For particulars 
of the remaining species I have been dependent entirely upon the 
descriptions and figures of the authors concerned, and in such 
cases no more can be done than to repeat certain statements 
which would seem of value for key-making. Thus I am not 
vesponsible for the rather remarkable assertion that LZ. catostomi 
possesses three cephalic arms, which, of course, renders the head 
quite asymmetrical. That is a feature which enables us to 
