ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 375 



coloration does not save more than a small percentage, but if it were not 

 established there would in some cases be no survivors at all. In some 

 Lepidoptera the male shows cryptic coloration, while the female does 

 not ; and the female is often much larger. In some such cases the 

 male insect hatches out first, in Lymantria dispar, 6 to 12 days before 

 the female ; in Macrotliylacea ruM, 4 to 10 days ; in Malacosoma neustria, 



4 to 10 days ; in Lasiocampa quercns, i) to 13 days ; in Saturnia pavonia^ 



5 to 13 days. The males hatched out first will have to wait some days 

 before mating, therefore cryptic colouring is more important for the 

 males. The female may be immediately mated, and the egg-laying may 

 be finished the day after hatching, if not on the same day. In twenty- 

 two species where the sexes are alike in colouring and size it was found 

 that the duration of the life-history up to the day of hatching is precisely 

 the same in the two sexes. Mating takes place at once, and survival is 

 not affected by conspicuous colours or the absence of cryptic coloration. 

 In species where both sexes are protectively coloured there is often an 



.interval between the hatching of the two sexes. Sometimes the males 

 emerge first, sometimes the females. Therefore both must have defences, 

 such as cryptic coloratiou. This does not save the majority, e.g., from 

 other Arthropods which do not depend much on vision ; but it saves the 

 requisite number of the surviving minority from the eyes of Mammals, 

 Birds, and other Vertebrates. J. A. T. 



Inheritance of Extra Bristles in Drosophila.— Edna M. Reeves 

 {Univ. Galifornia Ffiblications, Zoology, 1916, 13, 495-515, 1 fig.). 

 There is some evidence of Mendelian inheritance (with three factors) 

 concerned in the development of extra bristles in the fruit-fly (Drosophila 

 melanog aster Merg. = D. ampelophila Leow.) But there is also some 

 evidence in favour of regarding this as a fluctuating variation. Thickened 

 hairs gave evidence of a partial inheritance. There is no sex-linkage 

 involved in the extra bristles. Selection for an increased number of 

 extra bristles made no advance, the tendency being to return to the 

 conditions of four and five bristles. High-grade parents do not 

 produce high-grade off"spring ; in fact there is no definite relation between 

 parent and offspring as to the number of extra bristles. J. A. T. 



Coloration of Tiger-beetles. — Victor E. Shelford (Illinois 

 Biological 3Ionographs, 1917, 3, 395-532, 32 pis.). The colour-patterns 

 of Cicindelidffi are definitely related to elytral structures. Longitudinal 

 stripes in which pigment usually occurs lie in the area of the chief 

 tracheal trunks ; there are seven cross-bands in which pigment does not 

 develop ; the second and third and the fifth and sixth of these are often 

 joined to make one of each pair. Pigment usually occurs about the 

 bases of setse, which usually lie in the lines of the tracheae. In ontogeny 

 the elytra show a spotted condition corresponding to the system of cross- 

 bands and longitudinal stripes. The longitudinal stripes are usually 

 more pronounced. The origin of the various markings in the group is 

 traced. The colour-patterns and the structures to which they are related 

 constitute a mechanism, the directions of movement of which are limited, 

 i.e. easier in some directions than others. The colour-pattern plans 



