BRANCHIOPODA. 247 



mouth, tlicrcby assimilating tlieir functions to those of tlio second 

 inferior antennae, wliicli he calls antennulse. 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 

 I)roportion 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- 

 nidas, Straus — form the second family of the Monoculi of Jurinc. 

 The form of two of their antennae, Avhich 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 flea. 



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

 graphy of the Daphnise, 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, 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 Daphnise, 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 arc also two other but very short antennae 



* See Miill., Entom. genus Cypris ; Hist, des Monoc., second divis., Mon. a 

 coquilles bivalves, p. 159 — 179, XVII — XIX; Rand., Men., 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 f eve, 

 found in great abundance near the Gergovian mountain in the Puy-dc-DAmc, and 

 between Vichy-Les-Bains and Cussac. 



+ Daphnia selifera, Miill., Entom. 



X Daphnia cristuUina, Ejusd. Ibid. 



§ Raudohr has given it in the Fig. II, vii, tab. V, of these autcnnce. 



