NO. 13 STAPH YLINIDAE BLACKWELDER 49 



and projects somewhat from the median orifice (mo). The internal 

 sac (is) is rather large and nearly encloses the flagellum. Its ventral 

 surface is rather coarsely muricate, whereas the dorsal surface is 

 densely set with tiny spines or pointed processes. The internal sur- 

 face just below the flagellum at the point s is sculptured into minute 

 scalelike protuberances (fig. 9F), while just dorsal to the flagellum 

 is a small lobe projecting from the median orifice and very densely 

 clothed with long but fine hairs or setae. The two lateral lobes are 

 united on the ventral aspect except at the tip. They are very nearly as 

 long as the median lobe and very slender, with a small group of long 

 setae on the dorsal side at the tip. 



The outer surface of the aedeagus bears no sculpture or vesti- 

 ture, except for the frequent very minute pores which traverse the 

 integument. 



Comparative Morphology of the Family 



The following section is intended to give a brief review of the 

 variation within the family of certain of the more important charac- 

 ters as they are found in the series of species studied. There are very 

 probably many further modifications to be found in other species, but 

 the present study will serve to show the chief types and the general 

 trend of variation. 



the head 



The head capsule shows a great many modifications in structure as 

 well as a wide variety of form and sculpture. The proportions of 

 length to breadth are found in all stages from 2 :i to i :2 (figs. 10, 11). 

 The shape may. vary considerably within a single genus or even a 

 single species, or it may be fairly constant in a larger group. 



The dorsal surface of the head, or epicranium, is generally not di- 

 vided by sutures as in more generalized insects. Of the species studied, 

 only Tachyporus (fig. 10 C), Tachinus, and Erchomus (all in the 

 tribe Tachyporini) show any trace of the anterior part of the coronal 

 suture. A few species have a very short part of the suture visible 

 at the posterior margin of the epicranium. These include Psendopsis, 

 Paedcrus, Lathrotrop'is, Lithocharis, Trachysectus, Pinophiliis, Xan- 

 fholinns, Staphylinns, Philonthus, Cafius, Glenus, Acylophorus (fig. 

 II G), Qued'ms, Bolitohius (fig. 11 F), and Xenodusa. 



The frontal sutures are complete between the anterior tentorial pits 

 in all the Tachyporinae studied except Hypocyptus (fig. 10 D) as well 

 as the Habrocerinae and Oxyporinae. They were also found in this 

 condition in certain Oxytelini and Piestini. The following are noted 



