Miscellaneous. he 
Dimorphic Developinent and Alternation of Generations 
in the Cladocera. 
Dr. G. O. Sars has discovered a remarkable dimorphism and 
alternation’ of generations in Leptodora hyalina (“Om en dimorph 
Udvikling samt Generationsvexel hos Leptodora,’ Forhandlinger 
Vidensk.-Selsk. Christiania for 1873, p. 15, and plate). The de- 
velopment from the ordinary summer-eggs, as already described by 
E. P. Miller, is without metamorphosis and like that of ordinary 
Cladocera, the young when excluded from the egg agreeing essen- 
tially with the adult; while, according to Sars’s observations, the 
young are excluded from the winter-eggs in a very imperfect con- 
dition, quite unlike the known young of any other Cladocera, and 
pass through a marked postembryonal metamorphosis. In the 
earliest observed stage of the young of this form, the body is obovate, 
wholly without segmentation, the compound eye wanting, while 
there is a simple eye between the bases of the antennule, the 
swimming-arms (antennee) well developed, and the six pairs of legs 
represented only by minute processes projecting scarcely beyond the 
sides of the body. But the most remarkable feature is the presence 
of a pair of appendages tipped with cilia and nearly as long as the 
body, which are evidently homologous with the mandibular palpi of 
other Crustaceans, although these appendages have always been 
supposed to be wanting in the species of Cladocera. Two subsequent 
stages, gradually approaching the adult form, are described. The 
adults from the winter-eggs have no vestige of the mandibular palpi 
left; yet the simple eye (which is wholly absent in ordinary indi- 
viduals developed from summer-eggs) is persistent, and thus marks 
a distinct generation. Three stages of the young from winter-eggs 
are beautifully figured upon the plate accompanying the memoir. 
This remarkable species has, still more recently, been made the 
subject of a very elaborate memoir by Prof. Weismann of Freiburg 
(‘Ueber Bau und Lebenserscheinungen von Leptodora hyalina,” Zeit- 
schrift fiir wissensch. Zool. xxiv., Sept. 1874, pp. 349-418, plates 
33-38), who, however, had not observed the peculiar development 
of the winter-eggs. The occurrence of this genus in Lake Superior 
is noticed in this Journal, vol. vii. p. 161, 1874.—Silliman’s Ame- 
rican Journal, March 1875. 
On the Actinize of the Oceanic Coasts of France. 
By M. P. Fiscuzr. 
The Actinize of the oceanic coasts of France (comprising in that 
geographical region the Anglo-Norman isles) number thirty-one 
species :—Cerianthus membranaceus, Gmelin; Edwardsia Harassit, 
Quatrefages ; H. tumida, Quatref.; EH. Beautempsi, Quatref.; E. 
callimorpha, Gosse; Halcampa chrysanthellum, Peach; Peachia 
undata, Gosse; P. triphylla, Gosse ; Anemonia sulcata, Pennant ; 
Aiptasia Couchi, Cocks; Actinia equina, Linné; Metridium dian- 
thus, Ellis; Cereus pedunculatus, Pennant; Sagartia nivea, Gosse ; 
S. viduata, Miler (including S. troglodytes, Johnston); S. venusta, 
Ann. & Mag. N. Hist. Ser. 4. Vol. xv. 26 
