l'YCXOGONIDA. 



6 7 



Fig. 27: The same, from below. 



The embryonal legs have now been thrown off, and the development of the imaginal fore 



limbs has besmn. 



a. a. The palps ; b. b. the ovigerons legs. 



— 28: A palp (third larval stage) newly begun. 



— 29: An ovigerons leg (third larval stage) newly begun. 



Tab. II. 

 Fig. 1 — 7. Nymphon robustum Bell. 



Fig. 1 : First beginning of the embryo, lateral view. 



The embryonal legs are seen as distinct swellings. 



— 2 : Larva of the second stage, lateral view. 



The larva is still enclosed in its membranes (and egg-shell?), but the trunk is already seg- 

 mented, and the foremost pair of ambulatory legs are pretty long. 



a. The chelifori; b. the first embryonal leg enclosed by a dermal sheath; c. the second em- 

 bryonal leg; d. the proboscis; e. the first pair of ambulatory legs. 

 3: The proboscis, somewhat more enlarged, lateral view. 



Four cast-off sloughs of the proboscis are seen to be lying one within the other, with the 

 corresponding walls of the intestinal canal arranged in the same way. 



— 4: Larva of the second stage, lateral view. 



This phase is older than that of fig. 2 it having got the byssus-threads; the second pair of 

 ambulatory legs are also long, and the first pair distinctly articulated; on the other hand 

 only the two foremost segments of the trunk have been constricted, and the two hindmost 

 pairs of ambulatory legs scarcely begun. 

 /.' The second ambulatory leg. The other letters as in fig. 2. 



— 5: Free larva of the second stage, lateral view. 



A still older phase than fig. 4; nevertheless the last pair of ambulator}- legs have not yet 

 been fully developed, but the larva is free of the egg-shell and the membranes. 



— 6: The same, from below. 



The letters as in the preceding figures. 



— 7: Larva of the third stage, dorsal view. 



The embryonal legs and the byssus-threads are thrown off, but the newly begun imaginal 

 fore limbs have appeared. Of the ambulatory legs only one leg of the foremost pair has 

 been kept. 

 a. a. The chelifori; b.b. the palps; c.c. the beginning of the ovigerons legs. 



Fig. 8 — 12. Nymphon macronyx G. O. Sars. 



Fig. 8: Larva of the first stage, dorsal view. 



The embryonal legs and the proboscis are hidden by the trunk. 

 a. a. The chelifori; a.' a', the ducts of the byssus-glands. 



— 9: The same, from below. 



a. a. The chelifori; a', a', the duets of the byssus-glands; b.b. the first pair of embryonal legs; 

 c.c. the second pair of embryonal legs; (/. the proboscis; e. common ganglionic mass for the 

 embrvonal leg's. 



