52 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Convergence among Ectoparasitic Insects.* — N. C. Rothschild 

 discusses the repeated occurrence in different orders of similar structural 

 details. There may be convergence in reduction of mouth-parts, in 

 reduction of wmgs, in reduction of eyes, and so on. The degree of 

 parasitism in adult epizoic insects seems to be of less importance in con- 

 nexion with the reduction of eye than the absence of liyht. Many 

 similarities are found in the adaptations which enable the parasite to 

 hold on to its host, or to move about on it with safety. Many epizoic 

 insects " glide through the fur of the host as quickly as a seal travels 

 through water or a corncrake through grass." " The medium in which 

 a species exists exercises a most powerful influence on its evolution." 



Abdominal Extremity in Orthoptera.f — L. Chopard has made a 

 study of the various structures at the end of the abdomen in Ortboptera. 

 (1) The term suranal plate should be applied to the last tergite in 

 Blattidae, Mantid®, and adult Locustidas. The eleventh tergite of other 

 Orthoptera should be called the superior anal valve. (2) There are two 

 inferior anal valves, which, in some cases at least, are due to fusion of 

 the tenth and eleventh sternites. (3) The "subgenital plate" is of 

 heterogeneous nature, differing in different types. (4) The " oviscapt " 

 with sis or four valves is found in all female Orthoptera except Cur- 

 tillinas. Its superior valves are homologous with the lobes of the 

 male subgenital plate. 



Longevity of Males of Carausius morosis.| — G. Foucher obtained 

 two males among the numerous offspring which he reared from this 

 parthenogenetic Orthopteron. The male is 60 mm. in length as con- 

 trasted with 80 mm. for the female. It was very delicate and agile. 

 Its pairing with the female was observed. One lived for seven months 

 iind three days, a long time for a male Orthopteron. There is some 

 indication that starving the parthenogenetic females induces the appear- 

 ance of males, but more data are required. 



Intersexual Forms of Gypsy-Moth. §— Richard Goldschmidt con- 

 tinues his study of the Gypsy-Moth {Lymantria dispar) as regards 

 intersexuality. Each sex contains the factors of both sexes. Which 

 factors become potent depends upon the quantitative relation of the 

 two sets of factors. Both of them possess a quantitatively definite 

 strength of action or potency. In normal sex-distribution the right 

 combinations are regulated by the heterozygosis-homozygosis mechanism. 

 Different races differ, it is assumed, in regard to the absolute potencies 

 of these factors. Cross-breeding results in abnormal combinations, seen 

 in the intersexual forms. 



There is a remarkable seriation in both male and female inter- 

 sexnality. The series is the inverse of the order of differentiation of 



♦ Trans. Entomol. Soc. London, 1916, part v. (publ. 1917) pp. cxli-clvi (30 figs.), 

 t Arch. Zool. Exp6r.. Ivi. (1917) Notes et Revue, No. 5, pp. 105-12 (7 figs.). 

 X Comptes Rendus, clxv. (1917) pp. 511-3. 

 § Journ. Exper. Zool., xxii. (1917) pp. 593-617 (53 figs.). 



