86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



two species with a sclerotized tergite and one with a sternite. In the 

 present family there are apparently several more exceptions in the 

 sternites. Paederiis (fig. 30 D) has a distinct sagittate sternite of the 

 ninth segment which lies between and under the large valvifers. 

 Pinophilus (fig. 30 C) appears to have a large sternite also. 



In practically every species examined there is a pair of large 

 sclerites on the ventral surface which are interpreted as the valvifers. 

 In most cases, therefore, it is found that the coxites are entirely 

 lacking. Complete coxites with styli are found in all the Staphylinini, 

 Xanthopygini, Quediini, and Oxyporinae studied, and also in all the 

 Omaliini. This latter tribe is very dififerent from the others, however, 

 in that the genitalia are much elongated and have large membranous 

 areas between the sclerites. The first group includes Crcophilus (fig. 

 9 B, C) and Oxyporus (fig. 29 A, B). The Omaliini examined in this 

 regard were Gcodromicus (fig. 29 C), Tanyrhinus, and Latiiriiiiaeuni 

 (fig. 29D, E). In Oxyporus there are apparently no styli on the 

 coxites. In Gcodroinicus the coxites are two-segmented but lack styli. 

 In Lathrimaemn the valvifers appear to be fused to form an elongate 

 median ventral sclerite, bearing apically the two small coxites and 

 their styli. 



The sternite of the tenth segment is entirely membranous in all 

 members of the family, but the tergite is represented by a large broad 

 sclerite, the proctiger (figs. 9 C, 29 B). Apparently only a few species 

 possess the appendages of the ninth segment called the paraprocts 

 by Tanner. They are present in Creophihis (fig. 9 B, C) and other 

 Staphylininae, in Oxyporus (fig. 29 A), in Lathrimaeimi (fig. 29 D. 

 E) , and probably others. 



In Oxytelus (fig. 29 I) the entire ventral aspect of the ninth and 

 tenth segments is membranous. The dorsal side is composed of a wide 

 proctiger and a pair of narrow lobes at the sides. Micropcphis (fig. 

 30 A) is still more reduced. At first sight the eighth tergite and 

 sternite appear to be part of the genitalia, but the tergite bears a pair 

 of tiny but distinct spiracles. The genitalia form a more or less cir- 

 cular structure without any definite sclerites. 



DISCUSSION 



Variation and Range of Structure 



Though it has often been said that the beetles, and even the entire 

 class of insects, are characterized by a remarkable degree of uni- 

 formity of structure, a beetle almost always being immediately recog- 

 nizable as a beetle, yet it is equally true in both the order and the 



