8o Journal of Comparative Neurology and Psychology. 



laid at night, often not until "some weeks" after sexual union. After 

 the eggs are laid the mortality is great among the females. It is, 

 however, still greater among the males after sexual union, many dying 

 immediately thereafter. Before the eggs are laid, the female thor- 

 oughly cleans her ventral surface. The eggs, from 400 to 600 in 

 number, are fastened to the pleopods in clusters, much like bunches 

 of grapes. Immediately after laying the eggs, the female seeks a dark 

 place and there rolls from side to side, resting from i to 6 minutes on 

 either side and on the ventral surface. This reaction continues for several 

 hours and probably serves to fasten the eggs to the pleopods. Eggs 

 removed from the female die unless the embryos in them are well de- 

 veloped. It requires from 6 to 8 weeks for the embryos to hatch, 

 after which they remain attached to the mother continuously during 

 the first week and part of the time during the second. After the sec- 

 ond week they no longer return to the mother. If several mothers 

 with embryos are in the same dish, the embryos frequently crawl onto 

 the wrong mother. There is no evidence that the mothers recognize 

 their own young. The embryos moult 2 days after hatching. The 

 intervals between the following 5 moults vary from 5 to 18 days. 



Practically all the observations were made in the laboratory. It 

 is to be regretted that more work was not done in the field. Most of 

 the descriptions are worked out in detail. These together with 10 

 very good figures convey a very clear conception of the habits studied 

 and seem to show that the author made keen, thorough, careful ob- 

 servations. The literary merits of the paper, however, might have 

 been improved by careful revision. s. o. j^iast. 



Taverner, P- A. A Discussion of the Origin of Migration, Auk, 1904, 21, 

 322-333- 



Return of birds to the winter home is easy, that to the summer home 

 is hard"; to explain. The author discusses previous theories, and con- 

 cludes that sufficient emphasis has not been placed on the fact of the 

 great increase in the bird population at the beginning of the breeding 

 season. In southern latitudes some birds begin to breed early ; when 

 later breeders are ready to commence they find that food has become 

 scarce. The scarcity of food thus brought about was, Mr. Taverner 

 thinks, the chief cause of birds' having commenced the habit of seek- 

 ing a new home at the beginning of the breeding season. 



WALLACE CRAIG. 

 Rawitz, B. Die Unmoglichkeit der Vererbung geistiger Eigenschaften beim 

 Menschen. BioL Centralbl., 1904, 24, No. 12, 396-408. 



Rawitz argues vigorously against the inheritability of mental 

 traits in man. His standpoint is that of extreme materialism, g. w. 



