166 
BRITISH ENTOMOSTRACA. 
consist of exactly the same organs as in the animals of that 
genus, though, from their extreme minuteness and want 
of lengthened opportunities for examination, I have not 
been able to make out all the parts. The palpiferous 
mandibles, and the first pair of jaws with their branchial 
plates, are the only parts I have clearly distinguished, 
and they resemble in almost every respect the correspond- 
ing organs of the Cy prides. 
The mandible (t. XX, f. 5c) is formed of two pieces : the 
larger of the two, or proper mandible, as in the Cypris, 
being terminated at the superior extremity by a sharp 
point, and at the lower or incisive extremity by about six 
or eight pretty strong teeth ; while the other part, the 
palpus, consists of three or four joints, plentifully supplied 
at the extremities of the articulations with numerous setae, 
and a small branchial plate of one joint attached to the 
first articulation. The first pair of jaws (t. XX, f. 5 d) 9 as 
in the Cypris, consists also of two parts, the square plate, 
with the four fingers, the superior of which has two joints, 
while the others have only one, and are all terminated by 
a tuft of setae ; and the branchial plate attached, of an 
elongated oval form, furnished with fourteen long setae, 
which are given off from both sides. As these organs are 
so very similar to the corresponding organs in the Cypris, 
I have no doubt that the other parts (the lips and second 
pair of jaws) are also alike, and therefore that the suppo- 
sition of Desmarest, with respect to some of the inter- 
mediate feet being peculiar organs, is incorrect, and that 
as their use and situation indicate, they are all true feet, 
and used solely for locomotion, the posterior pair perhaps 
serving, in addition, one of the uses of the tail of the 
Cypris, that of cleaning the inside of the shell, for which 
they are well adapted, from their length and the great 
degree of mobility they possess. 
The appendix, or short tail, is of such an irregular 
figure, that until better opportunities occur for examina- 
tion, I shall not attempt a minute description. The in- 
ternal anatomy I have not succeeded in making out at all, 
