94 
BRITISH ENTOMOSTRAOA.. 
part, the carapace is marked with a series of circular, flat- 
looking canals (t. VII, f. 1 a), which resemble very much 
the canals described on the carapace of the Apus, and 
which probably serve the same purpose. 
The head is very small, compared with the size of the 
animal, flattened on the summit, and straight on its front 
margin, which terminates in a short, projecting beak. 
On its posterior surface it is marked near the edge with 
a strong ridge, which appears to commence just above the 
eye, and runs down to immediately above the heart ; 
while a similar elevated ridge seems to encircle the root 
of the antennae. 
The eye is of a moderate size, but smaller in propor- 
tion than in the pulex. 
The inferior antennae are small, compared with the size 
of the animal, the filaments being finely and densely plu- 
mose, but the antennules are well developed, compared 
with the jpulex; consisting of a short tubercle, which sends 
off several short setae. 
The sixth segment of the body sends off five projec- 
tions ; the two posterior being in the form of long spurs, 
and curved, the points reaching backwards and upwards, 
the other three being short and obtuse, all finely serrated. 
The fifth sends off two filaments, which are much shorter, 
proportionally, than in the two preceding species, but 
finely plumose. 
The abdomen is rather long, broad at the upper part, 
rather deeply sinuated at about half its length, and narrow 
towards the extremity. It is beset on the under edge 
with about fifteen teeth, the sinuation being free from 
them, and is terminated by two long, curved spines. 
The young are very numerous, and I have sometimes 
counted upwards of thirty born at one accouchement. 
When the ova are in the ovarium, and even when the 
young are considerably developed, they present a beautiful, 
green -coloured mass, showing through the transparent 
carapace. 
This is by far the largest species of the family I have 
