JOURNAL OF MICROSCOPICAL SCIENCE. 



EXPLANATION OF PLATES XIV & XV, 



Illustrating Mr. Edmund B. Wilson^s paper on ' The 

 Origin and Significance of the Metamorphosis of 

 Actinotrocha/ 



Pig. 1. — Very young Actinotrocha, lateral view. 



h, hood; vi, mouth; «^, stomach ; <?, anus ; «',«", rudiments of 

 arms. 



Fig. 2. — Ventral view. 



Letters as before ; ce, oesophagus. 



Fig. 3. — Older larva. 



Letters as before. 



Fig, 4. — Older larva. 



Letters as before ; a' , a", «', a*, w", arms. These four figures 

 copied from Metschuikoff. 



Fig. 5. — Still older larva of species "A" from Chesapeake Bay. 



p, ventral pouch ; i, intestine ; a, r, prteanal ciliated belt ; v, dorsal 

 vessel ; cor, mass of pseud-hsemal corpuscles. 



Fig. 6. — Opposite view, species " B." 



I, glandular lobe of stomach ; c, coecal appendages of pseud-hsemal 

 system. 



Fig. 7. — Ventral view. 



0, opening of pouch. 



Fig. 8. — Much later stage ; lateral view. 



Fig. 9. — Same stage ; dorsal view. 

 V, dorsal vessel. 



Fig. 10. — Full-grown larva of B. 



e, conical elevation of hood ; f;, a, rudiments of permanent tentacles. 



Fig. 11. — " Critical stage," species B. 



b, b, fibrous connections between pouch and intestine. 



Fig. 12. — Immediately after metamorphosis, species A. 



Fig. 13. — Twenty-four hours later. 



Fig. 14. — Twenty-two days later. 



a, tentacles ; e^^, epistome ; m, mouth ; in, intestine ; sf. stomach. 



Figs. 15 to 19. — Diagrams to illustrate the metamorphosis, 

 wi, mouth; a, anus; p. pouch. 



Fig. '2^.~Sahellaric(, from North Carolina. 



