452 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 46. 



United States National Museum, Washington, District of Columbia, 

 and in the Museum of Comparative Zoology, Cambridge, Mas- 

 sachusetts. 



The subject here considered was studied in the entomological 

 laboratory of the University of Illinois, of which it forms contribu- 

 tion No. 35. 



Subfamily TOlVrOCKRIDS'^G SohafTer. 



Tomocerime, Schaffer '96, p. 177. — Borner '06, p. 161. 



Tomocerini Schaffer '97, p. 35.— Borner '01, p. 60; '06, p. 161.— Absolon '03, 

 p. 108. 



Eyes twelve or none. AntennsB four segmented; third segment 

 much longer than the fourth; last two segments subsegmented. 

 Prothorax reduced, membranous. Mesonotum covering pronotum, 

 but not projecting over the head. Tibiotarsi one or two segmented; 

 clavate tenent hair present or not. Both claws present. Unguis 

 pseudonychiate, with basal folds and simple (not double) teeth. 

 Third abdominal segment longer than the fourth. Dentes three- 

 segmented, with stout basal spines; mucrones long, subcylindrical. 

 Anal segment with three cerci. Scales present, with longitudinal 

 ridges and transverse striae. Two genera, as follows: 



Eyes twelve; tibiotarsi two-aegmented; clavate tenent hair present. Tomocerus, p. 452. 

 Eyes absent; tibiotarsi one-segmented; clavate tenent hair absent. . Tritomurus, p. 469. 



Genus TOm6cERUS Nicolet. 



Tomocerus Nicolet '41, p. 67. 



There are six eyes on each side of the head (fig. 1). The antennae 



(fig. 2) are long, but exceed the body in length in only a few species 



of the genus. The short terminal antennal segment 



O O is often absent through mutilation; this segment and 



(2) f\ the third are subdivided into short rings, which in 



the latter segment often number one hundred and 



w fifty or more, except in young individuals. 



O The leg, in CoUembola, consists primarily of seven 



Fig. 1. -Tomocerus segments, five of whicli Were formerly termed, respec- 



FLAVESCENS, VAR. . , , ^ , 



ARCTicus. Eyes tively, coxa, trochanter, lemur, tibia, and tarsus, as 

 OF RIGHT SIDE, lu otlicr lusccts. Bomcr's ('02) comparative studlcs of 

 the segmentation of the legs of myriopods and insects 

 have led him to apply the term "tibiotarsus" to the so-called tibia 

 of CoUembola and to adopt de Meijerc's ('01) term praetarsus f or the 

 small segment that bears the claws. In Tomocerus the tibiotarsus, 

 functionally a single segment, is morphologically at least two seg- 

 ments, as shown by the presence of a suture just above the tenent 

 hair. Occasionally a second suture occurs as an abnormality, divid- 

 ing the tibiotarsus into three segments (fig. 3), which are probably a 



