264 
BRITISH ENTOMOSTRACA. 
from base to apex, and giving off two branches or rami, 
each of three joints, provided with rather long, plumose 
setae. The first and second of these joints have each one 
very long seta springing from their base, and the terminal 
giving off at its apex six of nearly equal length. The 
third pair (t. XXXIV, f. 5 m) is not unlike the preceding. 
The basilar portion, however, seems to consist of only one 
joint, which appears to constitute a lamellar appendage to 
the lower part of the ceplialo-thoracic portion of the body. 
It gives off two short rami, each single-jointed, and fur- 
nished with plumose setae. On the edge of the lower 
part of this portion of the body there is a short spine dr 
hook, similar to that observed near the first pair of foot- 
jaws. The fourth pair (t. XXXIV, f. 5 n) springs from the 
posterior thoracic segment of the body, and is very dif- 
ferent from the preceding pairs, being more adapted for 
the purpose of walking than swimming. It is slender, 
elongated, and directed outwards ; consists of four joints, 
and is simple, and not branched. The joints diminish 
in size as they approach the apex, which is either in form 
of a long, curved seta, with a row of short spines on its 
inner edge, or a short joint terminating in three short setae. 
On the median line of the body, between the last pair of 
foot-jaws and first pair of feet, we observe a broadish 
appendage (t. XXXIV, f. 5 j), of a horny nature, generally 
bifurcated, directed backwards, and capable of being 
elevated or depressed. It is a sort of sternum. On the me- 
dian line of last thoracic segment of the body, and toward 
the posterior extremity, we see two somewhat similar 
smaller horny tubercles, which M. Edwards considers 
may be regarded as the vestiges of a fifth pair of feet. 
Erom the external portion of the posterior part of this 
segment also, on each side, in the female, we see the 
external ovaries, two long cylindrical tubes, sometimes 
two or three times the length of the whole animal. 
According to Pickering and Dana, the internal organs 
of reproduction consist of a large pyriform organ, of a 
glandular appearance, situate just anterior to the stomach, 
