ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 495 



■disturbing the health of the host. The wasps die soon after the emerg- 

 ence of the male Xenos, seeming to become dried up. Infected wasps 

 are usually lighter in colour and more feeble in flight. 



Oogenesis is very peculiar. Very small larvae show strings of 

 spherical primitive ova on each side of the gut. These grow and later 

 break up, giving rise to eggs, each of which consists of a mass of nurse- 

 cells bearing a polar cap of cells derived from a primitive egg attached 

 to it. Yolk is formed from the contents of each egg, and when ripe 

 the eggs are scattered about all through the cavity of the body, and lie 

 imbedded in the fatty body. Maturation seems to occur through the 

 fusion of the second polar body with the pronucleus of the egg (!) 



The cleavage cells form a blastoderm which does not cover the whole 

 egg, and draws up to one pole to form the rudiment of the germ band 

 by a rearrangement and multiplication of its cells. Older embryos are 

 of the usual generalised type, but on account of their length are curled 

 up in the egg in a peculiar manner. 



The first larval stage, or " triungulin," gives rise through the loss of 

 its legs and degeneration of its internal organs, to the second or legless 

 larva, which is provided with median metameric protuberances in the 

 place of legs. The sexes begin to differ in external form after another 

 moult when peculiar asymmetrical muscles develop in the thoracic 

 segments. After another ecdysis the adult form appears. The female 

 protrudes the anterior extremity of her body, and lies with her ventral 

 side turned towards the dorsal surface of the wasp's body. The embryo- 

 logical data do not indicate any affinities between the Stylopida? and the 

 'Coleoptera, so the family may best be considered for the present as 

 belonging to the Strepsiptera. 



The attacks of the parasites are not confined to the female sex ; and 

 the sex of the host is at most only to a slight degree influenced by the 

 presence of Xenos larvae in the body. On the other hand, there is a 

 ivell-marked tendency for all the parasites in one wasp to develop the 

 same sex. 



Lepidoptera of North America.* — Harrison G. Dyar has accom- 

 plished the gigantic task of producing a new list of North American 

 Lepidoptera, with a key to the literature of this order of insects. He 

 has been especially assisted by C. H. Fernald, the late Rev. G-. D. Hulst, 

 and A. Busck. The work is intended to take the place of Smith's List 

 (1891), and to furnish a condensed catalogue comparable to Staudingei 

 and Rebel's catalogue of the Lepidoptera of Europe. The author places 

 the butterflies first, since they seem on the whole " higher " than the 

 moths. He follows with the Spkingidai, and Saturnians for the same 

 reason, although, in venation, they are more generalised than some of 

 the Noctuid groups. The list, as a whole, proceeds from higher to 

 lower forms, as in Staudinger and Rebel's catalogue. 



Mandibular Glands of Larval Lepidoptera.f — L. Bordas describes 

 these in Acherontia atropos, Pier is brassicce, and Stauropus fagi, — a pair 

 «of tubular glands in the anterior thoracic region, on each side of the 



&' 



* Bull. U.S. Nat. Mus., No. 52, 1902, pp. xix. and 723. 

 t Comptes Rendus, cxxxvi. (1903) pp. 1273-5. 



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