826 DR. W. A. CUNNINGTON ON PARASITIC 
instance, then, the effect is produced rather by an incision in the 
region of the genital apertures than by the combination of 
characters which has been already fully explained. 
The most striking characteristic of this species is the existence 
of only one pair of cephalic arms instead of two pairs. There 
seems little doubt from the relation they bear to the head-tubercle, 
that these correspond to the dorsal cephalic arms of species in 
which two pairs of arms are present. Such an important differ- 
ence from the common type might be considered sufficient to 
warrant a generic distinction for this species, but [have preferred 
to leave it for the present in the genus Lerneocera. 
Occurrence.—Sumbu, Lake Tanganyika, 13.10.04. From gill- 
arches of a large Clarias mossambicus. ‘Two specimens, one very 
incomplete. 
9. LERNHOCERA HAPLOCEPHALA, sp.n. (PI. I. figs. 4-7.) 
Description.—(Adult female.) Cephalic arms four, of about 
equal size, short and stout, without any indication of forking and 
being so placed as to form a particularly regular cross. The 
dorsal arms are simple and bluntly pointed ; the ventral differ 
from them only slightly, exhibiting an obvious swelling on their 
ventral aspects. The body is almost straight, unsegmented and 
cylindrical. The anterior third is slender, the body dilating 
gradually behind to become about twice as thick. Pre-genital 
prominence well marked, simple and not bilobed ; terminal 
portion of body rather slightly upturned and rotated through 
somewhat less than 90°. Immediately behind the junction of the 
arms with the body, and just external to the second pair of 
swimming-feet, a pair of rounded tubercles are situated, which 
project ventro-laterally. The egg-sacs are moderately long and 
tapering, about one-fifth length of body. They contain from four 
to five rows of eggs at their widest part. The eggs are approxi- 
mately round, and their diameter is about *] mm. 
Total length of largest specimen (excluding egg-sacs), 14°3 mm. 
Remarks.—This species is represented in my material by a 
considerable number of specimens from different sources, which 
would suggest that it isa relatively common form. Unfortunately, 
the bulk of the specimens have suffered severely from lack of care 
in preservation, having been preserved apparently in the same 
manner as their host, or even with it, and they are in consequence 
greatly shrunken and shrivelled. Jt is thus the more satisfactory 
that all these can be readily identified as belonging to this species 
by the presence of the characteristic ventro-lateral tubercle 
mentioned above. The single specimen from Tanganyika, on 
which the description is largely based, and which is figured on 
Plate I., is unluckily devoid of egg-sacs, but this defect is made 
good in one from the Nile (fig. 7), which happens to be damaged 
elsewhere. The Tanganyika specimen proves also considerably 
loager than any of the individuals from the Nile, which is doubt- 
less accounted for in part by the contracted nature of the latter. 
