No. 386.] REVIEWS OF RECENT LITERATURE. 163 
especially along the posterior margin. The author suggests the name 
proto-ephippium for this primitive protective covering of the resting 
egg. This structure is formed quite independently of fertilization, 
but before the resting eggs leave the ovaries and are transferred to 
the ephippium it is necessary that they be fertilized. In the absence 
of the male the empty ephippium is cast off and resting egg re- 
tained. If fertilization does not ensue, this process may be repeated 
several times in succession, as Weismann has already shown for the 
larger Cladocera. Some of the secondary sexual characters of the 
male, as, for example, the form of the intromittent post-abdomen, are 
not assumed until the last molt preceding the adult condition, the 
structure preceding this molt being of the female type. Attention is 
called to the cosmopolitan distribution of the species, and to its prefer- 
ence for small bodies of water rich in vegetation. ” It is, however, 
not infrequently found in our largest American lakes. Like some 
other Cladocera, Chydorus exhibit two periods of sexual activity in 
each year, one in April and May, the other in November and Decem- 
ber; the former is the more important, and affects only those in- 
dividuals found in small ponds likely to be dried up during the 
summer, while the latter is confined to colonies in larger bodies of 
water. It seems probable that some colonies. may never have a 
sexual period at all; at least some large ponds most thoroughly 
examined never once yielded a male or an ephippial female. 
CABE 
Rotifers of the Leman. — The first part of a superbly illustrated 
monograph of the rotiferan fauna of this Swiss lake and its neigh- 
borhood has been published by Dr. Weber.’ Owing to the absence 
of swamps and small bodies of water in this alpine environment the 
number of species recorded is not so great as in England or in 
Germany, though a very extensive list is presented. Each species is 
briefly described, the synonymy and the bibliography are given, and 
figures, often in natural colors, are liberally provided. The males 
and resting eggs are illustrated in some instances. We regret the 
absence of references to several important American lists in the 
bibliographies of the various species. American workers on this 
group will, however, find the paper of much interest, as many of the 
species figured are abundant in this country. GAK 
1 Weber, E. F. Faune rotatorienne du basin du Léman, Kevue Suisse de Zool., 
tome v (1898), pp. 263-354, Pls. X-XV 
