414 NATHAN FASTEN. 



EXPLANATION OF PLATE I. 



FIG. i. View of the tripartite eye as seen from the ventral surface of the larval 

 organism. The facet-like surfaces of the lateral (l.o.) and median (m.o.) ocelli 

 as well as the semi-lunar cups (c),and the pigment (p), can readily be observed. 

 X 1.637- 



