14 U.S. NATIONAL MUSEUM BULLETIN 2 79 



dorsal lobe three (DL3), and spiracular lobe (SL) (figs. 33 and 35). 



I have followed the above designation plus the following: lateral 

 lobe one (LLl), lateral lobe two (LL2), and lateral lobe three (LL3) 

 for the three main lobes of the lateral area (figs. 33 and 35) ; and ventral 

 lobe one (VLl), ventral lobe two (VL2), and ventral lobe three (VL3) 

 for the three main lobes of the ventral region (fig. 28). 



In addition I have designated three subdivisions of DL3 on abdominal 

 segments one through six as DL3a, DL3b, and DL3c (fig. 33). The 

 same terminology has been applied to the lobes of the thorax with the 

 exception that there are usually only one or two such lobes per segment 

 on the thorax. 



Illustrations 



The figures were done with the aid of a squared grid in the ocular 

 of a binocular stereomicroscope, using a Bausch and Lomb micro- 

 projector, or freehand for those wliich were diagrammatic. Sclerotized 

 areas are indicated by stippling and the heavier the degree of sclerotiza- 

 tion or pigmentation, the heavier the stippling. The degree of pig- 

 mentation of the different areas was found to vary direcdy with the 

 degree of sclerotization. 



Broken lines on the figures of the epipharynx are used to indicate a 

 zone of transition in texture. Broken lines on the thoracic and ab- 

 dominal figures denote secondary folds, whereas solid lines demark 

 the primary folds of the different segments. 



General Biology 



Adults and larvae of Trox and Omorgus usually are found associated 

 with animal remains (insects, fish, amphibians, reptiles, birds, mam- 

 mals). They are commonly found as one of the last visitors of mammal 

 and bird carcasses, or in the nests of birds and burrows of mammals, 

 especially those in which there is an accumulation of fur or feathers. 

 Vaurie (1955) in her monograph on the group included a section on 

 biology and information on the individual species where known. 



The adults of the North American species vary in size from about 

 5 mm. to 19 mm. Most species have rough dorsal surfaces, and they 

 are usually covered with a crusty induement consisting mainly of 

 particles of mud plus small pieces of debris from the media in which 

 they live. At least a portion of this induement is attained as the teneral 

 adults make their way from the pupal cells to the soil surface. When 

 disturbed, the adults rapidly deflex the head and pull all the legs tight 

 against the body in such a way that neither head nor legs are visible 

 from above. In this position and protectively covered as they are by 



