122 CRUSTACEA. 



hardly equal to one-third of the others; the body, properly so 

 called, inflated and almost ovoid; tail narrow and formed of six 

 segments. The colour varies greatly; some are reddish, others 

 whitish or greenish. The whole length of the animal is two 

 lines. This species is very common(l). 

 The second general division of the Lophyropa Branchiopoda, or 

 that in which the shell is formed of two valves united by a hinge 

 Ostracoda, Lat. ; Ostrapoda, Straus is composed of two subge- 

 nera, the first of which, Cythere, since the interesting and valuable 

 observations of the latter upon the second or Cypris, appears to 

 solicit a more profound examination than that of Midler, our only 

 authority with respect to its characters, in order that they may be 

 clearly defined. According to Miiller we find in the 



Cythere, Mull. Cytherina, Lam. 



Eight simple feet(2), terminating in a point, and two equally sim- 

 ple, setaceous antennae, composed of five or six joints, furnished with 

 scattered hairs. They are found in the salt and brackish waters of 

 the sea-coast among the Fuci and Confervae(3). 



Cypris, Mull. 



But six feet(4); the two antennae terminated by a bundle of setae 

 resembling a pencil. 



The shell forms an oval, laterally compressed body, with an arcu- 

 ated and convex back, or towards the hinge; the opposite side is 

 almost straight, and slightly emarginated or reniform. Before the 

 hinge and on the median line is the eye, forming a large, blackish, 

 round point. The intermediate antennae, inserted above, are shorter 



(1) Desmar., Consid., p. 364. For the other species, seethe same work, p. 

 361 364, L1V; Mull., Entom-, Cyclops; Jurine, Hist- des Monoc, p. 1 84, prem. 

 fam. des Monoc. a. coquille univalve; Rand., Monoc, I, II, III. 



(2) It is probable there are but six. See Cypris, note 4. 



(3) If these Entomostraca inhabit salt-water exclusively, it is easy to see that 

 Jurine and other observers whose geographical position limited their researches 

 to the fresh-water genera, could not have spoken of the former. See Mull., En- 

 tom., Cythere, and Desmar., Consid., p. 387, 388, LV, 8. 



(4) Four according to Randohr, and eight according to Jurine; the first consi- 

 dering the two last as appendages of the males, and the second looking upon the 

 palpi of the mandibles and the branchial laminae of each upper jaw the two first 

 feet of his second division of the body, those which he says are composed of but 

 one joint and terminated in a dentated spoon as so many feet. The latter does 

 not include in this number those which the former considers a3 sexual organs; he 

 states them p. 161, 166 to be five jointed threads issuing laterally from the 

 pouch of the matrix, of the use of which he is ignorant. 



