304 Prof. H. Karsten on Rhynchoprion penetrans. 



of the posterior feet is fringed or pectinated at its lower edge 

 with strong setae ; the broad coxse and femora, which are sharp 

 above and in front, are furnished with an emargination at the 

 extremities of the side of flexion ; from this the elastic tissue 

 by means of which the projection of the animal is effected, pro- 

 jects in the form of a pad or cushion. (The form and garniture 

 of the legs are shown in the figures of the animal in Plates VIII. 

 and IX.). 



In running, the two hind legs, which are then perfectly in- 

 active, are drawn along ; and only the four anterior feet move, in 

 alternate pairs. In leaping, the animals only rise a few inches. 



To the third or hindmost thoracic segment a pair of large, 

 nearly triangular, wing-like plates, lying close to the body, are 

 immoveably attached ; in their broadest part, which occurs in 

 the median line of the body, they attains nearly half the length 

 of the abdomen. Like the segments of the body, they are uni- 

 formly chitinous. Between these two wing-like plates the middle 

 of the first long but narrow dorsal half-segment is left uncovered. 



No so-called second pair of wings is present, although there 

 is a narrow lateral plate, which, like the wing, by which it is 

 completely concealed, is attached to the posterior thoracic seg- 

 ment, and applies its upper and lower extremities to the mar- 

 gins of the narrow first dorsal and ventral half- segments. (This 

 organ, with its stigma, is shown shining through the wing-lamina 

 in PI. VIII. fig. 3, and PI. IX. fig. I.) I cannot regard these 

 organs as a second pair of wings, both on account of their im- 

 moveable attachment, with the first pair, to the third thoracic 

 segment, and also on account of the occurrence of a stigma in 

 their upper extremities, by which they show themselves to be- 

 long directly to the integument of the body. 



Each of the two wing-like appendages of the third thoracic 

 segment bears on its upper portion two rather distant, strong 

 bristles, which are bent backwards. On some individuals I 

 found exceptionally only one of these bristles. 



A similar bristle springs on each side from each of the eight 

 dorsal half-segments of the abdomen, of which the first, which 

 is narrow, is not a complete half-segment ; but the others, with 

 the corresponding overlapping ventral half-segments, completely 

 surround the abdomen. 



Besides these complete chitinous half-segments, which are 

 united by a delicate folded membrane, and overlap each other at 

 the margins like the thoracic segments, there is, at the posterior 

 extremity of the body, a number of plates more or less cleft and 

 converted into variously formed appendages of the generative 

 organs, according to the sex of the individual. 



In the males the stigmata occur in the vicinity of the bristles, 



