BRANCHIOVODA,. 
247 
mouth, thereby assimilating their functions to tliose of the second 
inferior antennae, which he calls antennulae. The two threads com 
posing the tail unite on leaving the shell, and seem to form but 
one ; they serve, as he supposes, to brush out its interior. The female 
deposits its ova in mass, fixing them on plants or the mud by means 
of gluten. During this operation, which lasts about twelve hours, 
and in the largest species produces twenty-four eggs, she clings with 
her second feet, and in such a manner as not to fear the shock of the 
water. He collected some of these packets of newly laid eggs, and 
after separating them, observed the hatching of the young ones, and 
obtained a second generation without the intervention of the males. 
A female which had deposited her ova on the 12th of April, changed 
her skin six times between that period and the 18th of the following 
May. On the 27th of the same month she spawned a second time, 
and two days afterwards, on the 29th, a third. From this, he con- 
cludes that the number of these changes in the young animal is in 
proportion to the gradual developement of the individual ; that this 
developement can only take place by a general separation of an en- 
velope become too small to contain the animal; and that the size of 
the latter has a determined limit to which it must attain * * * § . 
The Polyropha of our third division — Cladocera, Lat. ; Daph- 
nidss, Straus — form the second family of the Monoculi of Jurine. 
The form of two of their antennae, which resemble ramified arms and 
serve as oars, and the faculty of leaping which they possess, have 
acquired for one of the most common species the name of the aquatic 
arborescent jiea. 
The first of these naturalists, who has given us an excellent mono- 
graphy of the Daplmioe, a subgenus of tliis division, establishes two 
new ones ; one by the name of Latona, characterized by antennae, in 
the form of oars, divided into three branches, and of but one joint f; and 
the other by that of Sida, which approaches other known subgenera 
of the same division, in having similar antennae, divided into two 
branches only, but of which one is composed of two joints, and the 
other of threej. The Daphniae, according to him, are distinguished 
from the preceding and from the Lyncei, inasmuch as one of the two 
branches of these oars is composed of three joints and the other 
of four. Jurine, however — Hist, des Mon. p. 92 — states, that each 
branch is composed of three joints ; but it seems that he did not 
include the first of the posterior branch, a very short one, it is true §. 
The last, in all these Lophyropha, is terminated by three threads, and 
each of the preceding ones gives out another ; these threads are either 
simple or barbed. There are also two other but very short antenn3e 
* See Miill., Eutom. genus Cypris ; Hist, des Monoc., second divis., Mon. i\ 
coquilles bivalves, p. 159 — 179, XVII — XIX; Rand., Mon., IV ; Straus, M^m. 
du Mus. d’Hist. Nat., VII, 1 ; Desmar., Consid., p. 380 — 386, LV, 1 — 7. Des- 
marest — Crust. Foss., XI, 8 — has figured a fossil species which he calls Cypris feve, 
found in great abundance near the Gergoviau mountain in the Puy-dc-DAmc, and 
between Vichy-Lcs-llains and Cussac. 
•f Daphnia setifera, Mull., Entom. 
X Daphnia crislallina, Ejusd. Ibid. 
§ Rnndohr has given it in the Fig. II, vii, tab. V, of these antcunjc. 
