38 THE ENTOMOLOGIST’S RECORD. 
parallel rows of bristles, and an additional bristle under the stigma. The first 
abdominal tergite bears two series of long hairs, the next six have a single series 
only. ‘The sternite of the second segment (i.c., first sternite) in the male bears one 
hair ventrally and two laterally, while in the female there is a lateral series of six 
hairs. The next five sternites in the male all bear two long hairs. In the female 
the third, fourth, fifth, and sixth sternites bear from seven to nine hairs. The 
seventh sternite in the female bears two long and some short hairs. The eighth 
sternite in the male is, as usual, enlarged, and bears many small hairs on its 
ventral surface, and three strong spine-like bristles at its apical margin. The 
ninth sternite in the female has a curved row of bristles along its hinder edge. At 
the posterior edge of the seventh tergite there is a long bristle with two smaller 
ones on each side of it in both sexes. The hinder coxe bear a transverse row of 
short stout hairs on their outer surface. The hinder edges of the tibise are deeply 
notched. They bear on their outer surface, near the hinder edge, one row of 
bristles. The hind tibie bear five pairs of bristles inclusive of the apical pair, the 
third and fourth pair are close together, a single bristle is placed between the fourth 
and apical pair, close to the latter. The bristles of the tarsi are very stout, these 
are absent, however, on the ventral surface medially, except at the apex. ‘The 
claws are very long, being more than half the length of the fifth tarsal joint. 
Length 3-3°5mm. 
The type specimens found by Mr. W. D. Cowan, in Madagascar, 
on Centetes ecaudatus, is in the British Museum. 
CERATOPSYLLA INCERTA, Sp. nov. (figs. 2, 5, 6).—A very small and pale species, 
having but one comb, and that on the prothorax, consisting of 28 teeth. The 
portion of the head anterior to the antennal groove is relatively much shorter in 
the male than in the female. The labial palpi are very short, being about half the 
length of the head. The metathoracic epimeron bears eighteen hairs in the female 
and twelve in the male. All the tergites of the abdomen bear two rows of bristles; 
the seventh tergite bears one long bristle at its posterior edge. All the tergites are 
much thickened internally (see fig. 6). The tenth sternite in the male is much 
reduced in size. On the surface of the middle hind coxe there are long hairs, and 
the second segment of the anterior tarsi is longer than the first. Length 2mm. 
I have examined specimens of this insect from Nyctinomus jugularis, 
Peters, found by Mr. W. D. Cowan, in Tamatave, Madagascar, and 
also from Nyctinomus brachypterus, Peters, found by Mr. Hart, in 
Sierra Leone. The type is in the British Museum. 
EXPLANATION oF Puate II. 
. Typhlopsylla tristis. Copulatory organs ¢. 
. Ceratopsylla incerta. Head. 
. Pulex madagascariensis. Copulatory organs ¢, 
. Typhlopsylla ingens. Copulatory organs ¢. 
. Ceratopsylla incerta. Copulatory organs ¢. 
. Ceratopsylla incerta. Abdominal tergites showing thickening of skeleton 
(diagram). 
Oop wpe 
Plebeius argus and Plebeius aegon. 
By. do) We CEUs BENS: 
On the morning of August 4th, 1899, I caught at Simplon specimens of 
undoubted P. argus and specimens of just as undoubted P. aeyon. The 
former was abundant, the latter rare, on the flowery banks on the left 
side of the valley directly above the village. The difficulty of defining the 
differences that exist between these closely allied species is marvellous 
when one considers the ease with which the males, at least, can be 
distinguished at the first glance. In comparing the males the follow- 
ing superficial differences were at once noticeable. P. aegon was of a 
more distinctly violet tint (7.e., had a more pronounced tinge of reddish 
in its tone), the costa of the forewings was more broadly white, the 
apex rather rounder, the outer margin also rounded, and the 
dark marginal border much more decided. The hindwings of P. aeyon 
