BRANCHIOPODA. 125 



tervention 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 concludes that the number of these 

 changes in the young animal is in proportion to the gradual deve- 

 lopment of the individual ; that this development can only take 

 place by the general separation of an envelope become too small to 

 contain the animal; and that the size of the latter has a determined 

 limit to which it must attain(l). 



The Polyropha of our third division — Cladocera, Lat.; Daph- 

 nides, Straus — from 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 arboresceiit Jiea. 



The first of these naturalists, who has given us an excellent mono- 

 graphy of the Daphniae, a subgenus of this division, establishes two 

 new ones; one by the name of Latona, characterized by antennae, in 

 the form of oars, divided into three branches, of but one joint(2); 

 and the other by that of Sida, which approaches other known sub- 

 genera 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 three(3). The Daphniae, according to him, are distin- 

 guished 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(4). 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 antennae — particularly in the females — situated at 



(1) See Mull., Entom. genus Cypris; Hist, des Monoc, second divis., Mon. a 

 coquilles bivalves, p. 159 — 179, XA^II — XIX; Rand., Mon., IV; Straus, Mem. du 

 Mus. d'Hist.Nat., VII, 1; Desmar., Consid., p. 380 — 386, LV, 1 — 7. Desmarest — 

 Crust. Foss., XI, 8 — has figured a fossil species which he calls Cypris f eve, found in 

 great abundance near the Gergovian mountain in the Puy-de Dome, and between 

 Vichy-Les-Bains and Cussac. 



(2) Daphnia setifera. Mull., Entom. 



(3) Daphnia cristallina, Ejusd. Ibid. 



(4) Randohr has given it in the fig., II, vii, tab. V, of these antennae. 



