78 MORGAN, 
PLATE sur. 
Drawn to same scale as figures of Pl. I (except Fig. 11, which is not so much magnified). 
Fic. 8 Young worm with three pairs of gill-slits. Dorsal view. (Stage 
VIIL.) 
Fic. 9. Young worm with (probably) four pairs of gill-slits. Only three 
were seen in the living larva. Dorsal view. (Stage IX.) 
Fic. 10. Young worm having probably six pairs of gill-slits. Only three pairs 
were seen in the living larva. The true number determined by surface views 
of preserved specimens, and from sections. Dorsal view. (Stage X.) 
Fic. 11. Oldest worm obtained from Tornaria. Length 26 mm. Side view. 
(Drawn by Dr. E. A. Andrews.) (Stage XI.) 
