372 Prof. G. J. Allman on Polytrema miniaceum. 



between the epimeron and the corresponding cpisternal piece ; 

 each of these apertures bears an oviferoiis sac. The glands can 

 secrete the two sacs in less than ten hours. 



In the genera Cyclopsma and Canthocanqdus the female 

 aperture is situated upon the boundary between the first two 

 abdominal segments. The reservoir and the two glands exist 

 as in Cyclops^ ; but here the orifices of the glands open at the 

 vulva, which bears directly the single oviferous sac. 



The oviferous sacs are secreted by layers one within the 

 other ; the bottom has only a single layer. 



In the male Cyclops quadricornis there are not, as has been 

 supposed, two genital apertures at the angles of the last tho- 

 racic somite, altliough two organs producing the spermato- 

 phores actually exist there ; but there is only a single orifice, 

 in the form of a fissure, at the posterior margin of the first 

 abdominal somite. 



Like the Cladocera, the Copepoda propagate with great 

 rapidity. A priori one might suspect in them an apparent 

 or actual parthenogenesis ; but my experiments show that 

 young animals isolated immediately after hatching never 

 reproduced, nor did females sequestered after their first ovipo- 

 sition ever produce new oviferous sacs and new eggs. ]\Iore- 

 over, in a state of nature, the males are sufficiently common to 

 render parthenogenesis quite unnecessary for the preservation 

 of the species. 



XLII. — Note on Polytrema miniaceum. 

 By Prof. G. J. Allman, F.E.S. 



To the Editors of the Annals and Magazine of Natural History. 



Gentlemen, 



Among the most abundant products of the dredge on the coast 

 of Mentone is a little, red, branched, coral-like body which at- 

 taches itself to various objects brought up from moderate depths. 

 It is so conspicuous that it must be familiar to most naturalists 

 who have studied the fauna of the Riviera, and was long ago 

 described by liisso under the name of Polytrema corallina ; 

 while, as De Blainville has pointed out, it appears to be iden- 

 tical with the Millepora miniacea of Linneeus, whose specific 

 name it must therefore receive. 



With the exception, however, of some suspicions of its 

 rhizopodous affinities entertained by Gray and by Dujardin, 

 its real nature appears to have been entirely misunderstood, 

 systematic writers having placed it eitlier among the true 



