ABSTRACTS : ENTOMOLOGY 257 



that the lead-ziuc type is somewhat later than the pyritic type and that 

 the minerals of the former commonly line vugs or fractures in those of 

 the latter. It is believed, however, that the lead-zinc mineralization 

 followed close upon the heels of the pyritic mineralization, and that the 

 two types represent merely successive epochs in one great vein-forming 

 period. Although the mineral veins cut the monzonite porphyry dikes 

 and stocks, it is believed that both came from a common deep-seated 

 source, the ore-bearing solutions following the monzonite intrusion after 

 a short interval. 



Microscopic studies of the pitchblende ores indicate that they repre- 

 sent a local and unusual variation in the sulphide mineralization of the 

 region. It is believed that the pitchblende was deposited during the 

 earlier or pyritic mineralization, that it was afterward fractured, and 

 that the fractures thus formed were filled by sulphides of the later or 

 lead-zinc mineralization. The general geologic relations and the ab- 

 sence of characteristic high-temperature minerals in the deposits of 

 Quartz Hill, as well as in those of Cornwall and the Erzgebirge, indicate 

 that the pitchblende was deposited under conditions of moderate temper- 

 ature and pressure. Unlike the European pitchblende, however, the 

 pitchblende of Quartz Hill is not associated with nickel and cobalt 

 minerals, which so far as known have never been found in that region 

 even in small quantities. The occurrence of pitchblende in pegmatite 

 as well as in mineral veins of the type here described shows that 

 the mineral may also form under conditions of high temperature and 

 pressure. E. S. B. 



EXTOAIOLOGY. — On interspecific mating in Phengodes and inbreed- 

 ings in Eros. H. S. Barber. Proceedings of the Entomological 

 Society of Washington 16: 32-34. March 23, 1914. 



Females of a species of Phengodes easily distinguished from P. 

 laticollis in both sexes of adults and also in the larval stage were con- 

 fined with males of P. laticollis. In most cases the male did not recog- 

 nize the female; but some did, and in two instances there was mating 

 of a short duration. One female deposited three infertile eggs; the 

 other 48 fertile and infertile eggs. In the latter case some embryos 

 developed but did not issue; ten larvae issued, all but two deformed and 

 unable to feed; these two, which lived and fed for fifteen months, 

 showed the specific characteristics of the male. 



It is pointed out that most groups of insects have some obstacle 

 tending to prevent inbreeding and that those which have no obstacle 

 are usually somewhat degraded and inclined to form numerous local 



