112 ANIOJAL EEPOET. 



observed copulation in C^pris, and tlie peculiar organs represented in the plate 

 of Cypris seem to be restricted to the male, so that it is certain that the sexes 

 are distinct. 



These mmute creatures moult frequently, casting off in the process the minu- 

 test hairs as well as the shell. 



This sub-family contains two genera, both of which are represented by a few 

 abundant species within our limits. 



GENUS 1, Cypris, Muller. 



Characters. — Antennae of the second pair furnished at the end with a bundle of 

 long hairs, by means of which the animal swims freely in the 

 water. The structure is that of the sub-family. 

 It is very difl&cult to characterize the species, and it will be necessary to rely 



chiefly on the figures, since there is little variation in internal structure between 



the species. 



Cypris vidua, Muller. (?) 



Bibliographtj . — Cypris vidua, Muller, Zool. Dan. Prod. No. 2384. 

 Latreille, Hist. Nat. Crust., IV. 245. 



-Bosc, Man. d'Hist. Nat. Crust. 

 -Desmarest, 385, t. 55, p. 4. 

 -Baird, Trans. Berw. Club, ii. 152. 

 -M. Edwards, Hsst. Nat. Crust., iii. 399. 



Monoculus viduus, Gmelin, Linn. Syst. Nat., 3002, No. 42. 



Manuel, Enc. M6th., vii., 726, No. 36. 



Jurine, Hist, Nat. Monoc, 175. 



Bees, Cyclopedia, art. Monoc. 



Monoculus viduatus, Fabricius, Ent. Syst., ii. 496. 

 (I here give Dr. Baird's description verbatim for comparison with the figure.) 

 Description. — " Shell of oval form, a little sinuated on the under margin, and 

 beset all round with dense, fine, short hairs. The color is duU white, and the 

 valves are distinctly marked with three black, somewhat waved fasciae running 

 transversely across the shell at equal distances, the most anterior of the three 

 being smallest. Posterior margin rather narrower than anterior." 



This species, if it be the one figured beyond, is the most a.bundant of this 

 family here, inhabiting all the pools and lakes. It is quite small, appearing as a 

 small speck, either floating on the surface or swimming rapidly about, with a 

 sort of running motion, reminding one of the haste of an excitable man, in its 

 seeming uncertainty and briskness. In figure 1, the shell is represented as trans- 

 parent, to indicate the position of the organs. The size and shape of the dark 

 bands upon the shell vary in different individuals. 

 (SeePlateNo. XVII. fig. 1.) 



Cypria neglecta, Herrick, 



This species is apparently different from aniy other which I have seen described 

 The sh^ is very small, little exceeding .01 in. in length. The shape is, as seen 

 from the side, a very perfect oval, not sinuate below, but narrower posteriorly 



