1892.] 



The BRITISH NATURALIST 



In many of the Quediida^, Staphylinidae, and Pcederidse {Lathrobunn, 

 Poedcms, Stiiicus, etc.), and m Oxyporiis nifits, tlie seventh ventral 

 segment is more or less deeply notched in the male, while being 

 rounded in the female. Many Quediidae, and some Staphylini and 

 Philonthi, have this emargination preceded by a smooth (triangular 

 or oblong) space ; others, Philonthiis csneiis for example, have the 

 borders of the excision membranous ; while in P. cruentatiis the notch 

 is nearly, and in P. fimitcirius is sometimes completely filled up by 

 membrane. Some species of Lathvohium {elongatuni, borcale, etc) have, 

 in the male, two tufts of dark pubescence on the seventh ventral 

 segment, enclosing an impressed space. In the male of Stilicus 

 fvagilis the fifth ventral segment bears an oblong tubercle surrounded 

 by cilia, and the sixth has a deep excavation with raised edges. In 

 Blediiis fracticornis, etc, the sixth ventral segment of the male is 

 emarginate, but the notch is filled up with membrane ; and in the 

 males of several species of OxyteUis the sixth segment is furnislied 

 with tubercles, which are red in insecatus and laqueains, and pale in 

 sculpUiratiLS. AcfognatJms mandibularis has a tubercle in the middle of 

 the first abdominal segment. The genus Stenus presents a great 

 variety of sexual characters, mainly consisting of notches in 

 the margins of some and keels on others of the segments, but 

 S. providus and S. lustrator present the peculiar feature of tufts of 

 curled hairs on the ventral abdominal segments of the male, while 

 S. juno and S. speculator have in the same sex, tufts of hair between 

 the middle coxae Among the Clavicornia, out of a great variety of 

 modification of the abdominal segments, it will suffice to mention that 

 the most frequent sexual alteration is an emargination or sinuation of 

 the hind margin of the sixth ventral segment, as. in the males of some 

 Scyiiiuus, Coccinelln, Euplcctus, etc. In this last genus other species 

 have the ventral segments foveolate, while E. nubigena has the 

 whole abdomen longitudinally sulcate beneath. The males of 

 the genus Meligethes are often furnished with a tubercle or keel on the 

 last segment {ochropiis, brmmicoriiis, ovatus, etc), while M. bideiitatus 

 has two tubercles in the same position. The male Clavigcr foveolatiis 

 has the sixth ventral segment tuberculate at the apex. In Dcniicstcs 

 vulpinus and frischii the male has a tuft of brown bristles on the fourth 

 ventral segment, while in the same sex of iiiiirijiiis, lardariits, and 

 undiilatus, the tliird and fourtli segments are so tufted. Tlie males of 

 Cctoma have the first five segments of tlie abdomen longitudinally 

 impressed in the middle ; Agrilus aiigustulns has the first ventr d 

 segment of the male with two tubercles. The genus Malihclcs 

 presents, in the males, a very complicated development of some of 

 the ventral abdominal segments ; the penultimate segment is usually 

 semicircularly or triangularly notched, the last segment is often much 



