ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 607 



Male Organs of Scatophagy.* — W. Wesche describes the male 

 genitalia of Scatqphaga lutaria and S. stercoraria, two common flies, 

 related to onr smaller house-fly, Homalomijia canicularis, but predaceous, 

 with longer and more setose legs, stronger wings, and more highly 

 •developed teeth. The males are variable in size, some smaller, and 

 others, contrary, to the general rule, larger than the females. In mating, 

 the female is seized with a sudden spring (e.g. when killing prey or 

 feeding), and forcibly held, though sometimes struggling fiercely. The 

 male genital armature is suited for holding the female, and consists of 

 no less than ten separate pieces with distinct functions. But, as Berlese 

 has noted in regard to Musca domestica, the male, after seizing the 

 female, is passim. It is the ovipositor that is forced into the cavity of 

 the hypopygium, and its soft parts fit into and round the complicated 

 armature of the male. The author describes the genital armature ; 

 notes that S. merdaria is, as Verrall stated, a mere variety of S. stercoraria ; 

 and points out that mutual sterility between nearly allied species is 

 largely due to mechanical obstacles, as in the case of 8. lutaria and 

 8. stercoraria. 



Alimentary Tract of Silphidae.f — L. Bordas finds that this is 

 remarkable in its length, its numerous internal plaits, the rudimentary 

 nature of the gizzard, the minute structure of the hind-gut, the presence 

 of a terminal ampulla somewhat analogous to the rectal vesicle of 

 Dysticidffi, and the occurrence at the end of the gut of what seem to 

 •correspond with the rectal glands of Lepidoptera. 



Tracheal Gills on Legs of Larval Perlid.J — L. Lauterborn 

 •describes the structure and behaviour of the larva of Twniopteryx 

 nebulosa, which bears tracheal gills on a situation not before observed, 

 namely on the coxae of the legs. Palmen has distinguished (1) pro- 

 sternal and sternal tracheal gills on the first ventral thoracic sternite ; 

 (2) anal tracheal gills ; (3) pleural tracheal gills on the sides of the 

 thorax ; and (4) lateral abdominal tracheal gills. A fifth set — coxal 

 tracheal gills — must now be recognised. 



Formation of Chorion in Pyrrhocoris apterus.§ — A. Ivohler con- 

 firms Korschelt's account of the formation of the chorion as a secretory 

 process, not as one of cell-modification. Beaker-like openings were 

 rightly interpreted by Leuckart as micropyles. The vitelline membrane 

 is not present when the secretion of the first chorionic layer (endochorion) 

 begins, it appears contemporaneously with the beginning of the internal 

 lamellar layer of the exochorion. 



Systematic Position of Hemimerus.|| — K. W. Verhoeff discusses the 

 opinion of some authorities that Hemimerus (living on rodents) is a sort 

 •of intermediate form between Blattodea and Dermaptera, but nearer the 

 latter. He gives his reasons for concluding that Hemimerus is in no 

 .sense a transition-type, that it undoubtedly belongs to the Dermaptera, 



* Journ. Quekett Micr. Club, 1003, pp. 411-6 (1 pi.). 



t Couiptes Rendus, cxxxvii. (1903) pp. 344-6. 



% Zool. Anzeig., xxvi. (1903) pp. 637-42 (2 figs.). 



§ Tom. cit., pp. 633-6 (4 figs.). 



|| SB. Ges. Naturf. Berlin, 1902, pp. 87-9. 



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