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merits in both male and female; the fourth, fifth, sixth, and 

 seventh are of nearly equal size and shape in the male ; 

 and the fourth, fifth, and sixth are similar in the female. 

 The tergum of the first segment is broad, flattened and 

 cushion-like, projecting slightly caudad over the second 

 tergum. The sternum of the first segment is unchitinized, 

 appearing as a narrow, membraneous space between the 

 metasternum and the well-chitinized sternum of the second 

 abdominal segment. This second sternum is traversed by a 

 transversal, elevated line or carina, which lies almost midway 

 between the cephalic and caudal margins of the sternum. 

 This carina does not, however, represent a suture. The 

 terga of the first seven segments in both sexes are separated 

 from the sterna by a pleural membraneous fold. In this 

 pleural membrane the spiracles, which occur only on the 

 first seven segments, are located. The terminal segments 

 differ in the sexes, and they must be considered separately. 

 In the * female the tergum of the seventh segment is 

 longer than the sternum, and bends somewhat ventrad, 

 forming, with the much reduced eight and ninth segments, 

 a sort of hood over a space partly enclosed by this hood, 

 partly by a bluntly pointed, caudad-projecting process of 

 the narrow sternum of the seventh segment, and partly by 

 the margins of this segment. This space is called the 

 vaginal vestibule ; in it lies the vaginal opening. The eight 

 segment is much reduced and compressed. Its sternum, 

 with the outer aspect facing cephalo- ventrad, forms the 

 roof of the vaginal vestibule, and is bordered by a thin, 

 distinct margin. The ninth segment is much more reduced 

 than the eight, and it usually lies retracted between and 

 almost concealed by the slightly projecting lateral margins 

 of the eight segment. It presents two, small, lateral lobes or 

 flaps, and a narrow sternal connecting piece. 



* The sclerites of the caudal segments of the female can be much better studied 

 hi fresh specimens than in dry specimens. 



