June, 1917-] Hungerford: Life History OF A Boatman. 115 



Femur. 



Prothoracic leg 



Mesothoracic leg 



Metathoracic leg 291 



Color. — When newly hatched, the color is transparent white, the 

 red eyes possessing the only conspicuous coloring matter. The nymph 

 darkens gradually with age, coming finally to a mottled brown, of 

 rather indefinite pattern. 



Structural Details. — The nymph appears exceedingly flat. The 

 abdomen is fringed with lateral spines, which on the lateral margin 

 of the last four segments, are quite regularly arranged. There are 

 four spines of unequal length on each. First, a comparatively short 

 spine which is followed by one somewhat longer, and this, in turn, 

 is followed by a long spine, immediately caudad of which, at the 

 latero-caudal point of the segment is a very small spine. On the 

 dorso-lateral surface near the rear margin of each segment is to be 

 found a fine hair. The caudal end of the abdomen bears two short 

 spines, and several pairs of long ones. The eyes are relatively small 

 in comparison with the width of the head. In later instars they be- 

 come increasingly large as the nymph advances. This point has been 

 noted by Dr. Abbott in the case of R. acuminata. 



The limbs are more clumsily set up than in the more advanced 

 nymphs ; especially is this true of the forelegs. Here the pala is 

 studded with tiny pegs on its inner surface and equipped with the 

 characteristically strong spines and long bristles of the older form. 

 The pegged depression on the inner face of the pala occupies but the 

 outer half of the segments, as shown in the sketch of fifth instar leg, 

 PI. IX. fig. 10. Compare this with that of the adult, PL IX, fig. 12. 



The mesothoracic legs are angular limbs, terminating in two 

 long, slightly incurved claws which are larger than the tarsus itself. 

 They are sparsely clothed with bristles. The metathoracic limbs end 

 in long tarsi. They are fringed with about two dozen long hairs in 

 one row, and further equipped with two rows of stiff short spines. 

 The tarsi terminate in a pair of long slender claws, about one third 

 as long as the tarsus itself (see fig. 6). The tibia is slightly thicker 

 than the tarsus and is clothed in a few stout bristles arranged in 

 rows. It is provided near the distal end with a pair of longer bristles, 



