NO. 13 STAPH YLINIDAE BLACK WELDER 83 



connected by a semi-membranous band ; the median orifice is at the distal end, 

 and the median foramen slightly in front (or basal) on the ventral face. These 

 two openings are separated only by a chitinous plate formed by the basal part 

 of the lateral lobes which are extremely reduced. 



This description of XanthoUnus glahratus (p. 499) is equally ap- 

 plicable to our species, X. picipcniiis. In Metoponcus the basal part 

 of the median lobe is much more elongate and the lateral lobes are 

 more slender than in Xantholinus. 



In some forms there are more heavily sclerotized bars or struts in 

 the median and lateral lobes. They are apparently strengthening or 

 supporting structures and frequently articulate with each other. In 

 Hypocyptiis (fig. 28 A) the lateral lobes each bear three of these 

 structures, articulating with each other and with a fourth pair con- 

 nected to the median lobe. This latter pair is thought to be the pair 

 of median struts mentioned by Sharp and Muir (1912). The lateral 

 lobes are present on all forms examined. In Xantholinus (fig. 28 F) 

 and Metoponcus they are very small and not specially modified. In 

 Cafius they are also rather short but are otherwise similar to the other 

 Staphylinini. Hypocyptiis (fig. 28 A) represents the greatest develop- 

 ment of these organs in point of size. 



In Micropeplus (fig. 28 C) the lateral lobes arise from the sides 

 of the median lobe and unite for a short distance on the dorsal surface. 

 They are flat and unmodified and do not extend as far as the tip 

 of the median lobe. 



The genitalia of the female consist of the eighth, ninth, and tenth 

 segments of the abdomen and their appendages. The eighth segment 

 is present as a distinct tergite and sternite ; the ninth segment is mem- 

 branous except for a pair of three-segmented appendages and oc- 

 casionally a sternal sclerite ; and the tenth segment is represented only 

 by the tergite. This is substantially the characterization given by 

 Tanner (1927) for beetles in general. 



The members of the Staphylinidae for the most part appear to be 

 difi^erent from any forms studied by Tanner in the amount of reduc- 

 tion and loss of parts. Only a very few of the species included in the 

 present study have any coxites or styli, the valvifers are absent in 

 at least one species, and the paraprocts are frequently lacking. The 

 one Staphylinid studied by Tanner. Creophilus villosus, is one of 

 the very few which possess all the typical structures. 



The eighth tergite and sternite are generally not specially modified 

 in the female. They are broadly rounded as in Oxyporus (fig. 29 A) 

 or truncated as in Aleochara (fig. 30 E). The only outstanding ex- 

 ceptions are in tlie subfamily Tachyporinae, where there are very 



