1892.] 



THE BRITISH NATURALIST. 



246 



THE SECONDARY SEXUAL CHARACTERS OF 

 THE BRITISH COLEOPTERA. 



BY JOHN W. ELLIS, M.B. (vic), F.E.S. 

 (Continued from p. 235). 



Abdomen. —The extreme variety of sexual differences presented by 

 the abdominal segments precludes anything like a systematic ana- 

 tomical arrangement of these characters. Taking the peculiarities 

 connected with the dorsal segments of the abdomen first, we notice 

 that in Gnoriuius the pygidium — that is the exposed last abdominal 

 segment— is plain in the male, but bears two tubercles in the female, 

 especially evident in G. variabilis. The male of Bryaxis lielfevi has a 

 small tubercle bounded by a semi-circular fossa on the first segment. 

 But it is in the smaller Brachelytra that we find the greatest number 

 of sexual abdominal variations. Thus the male Cevanota nificovnis has 

 a transverse raised plate on the second, tubercles on the third and 

 fourth, and the sixth seo^ment depressed with three elevations near 

 the apical margin. Homalota vicina has a distinct tubercle on the 

 second segment of the male, very indistinct in the female ; H. cnspidata 

 has two tubercles on the third, fourth, and fifth segments in the male; 

 a group of the same genus containing //. currax, langiiida, insecta, &c., 

 has a distinct tubercle on the sixth segment in the male ; in H. 

 circeUaris the male has a tubercle on the sixth and two on the seventh 

 segments ; the same sex of H. depvessa has one tubercle on the sixth 

 segment and four on the seventh ; H. liepatica has two raised lines 

 converging behind, on the sixth, in the male ; Leptusa analis has, in 

 the male, a keel on the sixth and one on the seventh segment, while 

 its ally, L. fiunida, has a tubercle on the sixth and a keel on the 

 seventh. The genus GyrophcEna offers an admirable illustration of the 

 variety of sexual sculpture in allied species. G. pulchella has a horse- 

 shoe-like elevation on the sixth dorsal segment ; G. affinis has a 

 tubercle at the apex of this segment ; H. poweri, genhlis, nana and 

 minima have this segment furnished with four short ridges ; Ice^vipennis 

 wnth four tubercles ; fasciata with six short ridges ; while lucidida has 

 the surface of this segment finely granulated. In all these species 

 the same segment is perfectly smooth in the female. Many Homolat^ 

 {nitidida, vici7ia, pagana, etc.), have the dorsal surface of the seventh 

 segment of the male covered with fine granulations ; in gyamniicola 

 these are especially distinct, and scattered over the sixth as well as 

 the seventh segment ; and in aiitiimnalis, both sixth and seventh have 

 oblong granulations. I/omalota occulta has the sides and apical margin 

 of the last dorsal segment distinctly raised in the male. Deinopsis 

 erosa has the sixth segment of the male truncate and the seventh 

 slightly notched ; while in the female the margin of the sixth is wavy 



