372 Prof. G. J. AUnian on Polytreina ininiacouin. 



between the e2)iineron and the corresponding episternal piece ; 

 each of these apertui'es bears an oviferous sac. The glands can 

 secrete the two sacs in less than ten hours. 



In the genera Cijclopsina and Cant/iocatiipfus 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 ivithin the 

 other ; the bottom has only a single layer. 



In tlie male Cyclojys quadricornis there are not, as has been 

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

 racic somite, although 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 ^friori 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. More- 

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

 render parthenogenesis quite unnecessary for the preservation 

 of the species. 



XLII. — Xote on Polvtrema miniaceum. 

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



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



Gentlemen, 



Among the most abundant products of the dredge on tlie coast 

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

 taches itself to various objects brouglit uj) from moderate de])tlis. 

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

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

 described by Risso under the name of Polytrema coralUna ; 

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

 tical with the MiUcpora miniacea of Linnaeus, 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 either among the true 



