ORDER BRANCHIOPODA. 
333 
while the lower, on the contrary, present more ; also by rea- 
son of its body, which gradually grows slender towards its , 
posterior extremity, so that it appears to have no tail, at least 
abruptly formed, and its under part is armed, in the female, 
with a sort of horn, curved backwards. The cyclops castor, 
and some others, whose lower an teniae and mandibulary 
palpi are divided beyond their base into two branches, may 
also compose another group. That which Dr. Leach desig- 
nates under the generic name of CALANUS, might, indeed, 
form a subgenus proper, if it were true that the animal of 
which it is the type had no inferior antennae. But has he 
ascertained this point himself, or does he speak of it only after 
Muller ? This I know not. 
Cyclops quadricornis, Monoculus quadricornis, Linn., 
Mull., Entom. xviii. 1 — 14; Jurine. Monoc. i. ii. iii., has all 
the antennae simple, or without divisions. The lower have 
four articulations, and their length scarcely equals the third 
of the upper; the body properly so called is tolerably inflated, 
and almost ovoid ; the tail is narrow, and composed of six 
segments. The colour varies much ; some are reddish, others 
whitish or greenish. The total length is two lines. This 
species is very common. — Desmarets’ Consid. p. 364. See, 
for the other species, the same work, p. 361 — 364; Mull. 
Entom. G. cyclops, Jurine Hist, des Monoc. p. 1 — 84, first 
family of the Monoculi with univalve shell, Eamd. Monoc. 
i. ii. iii. 
The second general division of the branchiopodous lopliy- 
ropa, those whose testa is formed of two valves, united by a 
hinge (our Ostracoda, or the order of Ostrapoda of M. 
Straus), is composed of two subgenera, the first of which, that 
of Cytherea, appears to us, since the valuable researches of 
this naturalist on the second (cypris), to require, for the pur- 
pose of establishing its characters in a less equivocal manner, 
