32 CORA J. BECKWITH. 



Explanation of Plate II. 



Fig. 7. Embryo of Amia in which the lateral line anlage is first visible in section 

 but not in surface view. a. p., auditory pit. X 2 °- 



Fig. 8. Section along line a-b, Fig. 7, showing the first appearance of the anlage 

 of the lateral line, ec, ectoderm ; ht., heart; n.t., neural tube; ntc, notochord ; 

 p. a. 1. 1., post-auditory lateral line. X I ^>7- 



Fig. 9. Embryo of Amia showing the auditory pit. The lateral line anlage is 

 visible as ridges, in both head and body regions, a. p., auditory pit; i.o.l.l. infra- 

 orbital lateral line; o.m.l.L, opercular mandibular lateral line; p. a. 1. 1., post-audi- 

 tory lateral line; s.o.l.L, supra-orbital lateral line. X 2 °- 



Fig. 10. Section along line a-b, Fig. 9, showing the thickening of the inner layer 

 of ectoderm to form head lines, ec. , ectoderm; i.o.l.l., infra-orbital lateral line; 

 n.t., neural tube; op. v., optic vesicle ; s.o.l.L, supra-orbital lateral line. X I ^7- 



