PLATE 3 



EXPLANATION OF FIGURES 



R. sylvatica. Brains after fixatioo. Representative specimens. Note par- 

 ticularly the shape of the optic lobes and fore-brain. 



22 Control larva. 5/3 to 5/23/18. Alive: Tot., 36 mm., B., 15.5 mm.; 

 fixed: Tot., 34 mm., B., 13 mm. 



23 Control frog. 4/14 to 6/5/18. Alive: B., 15 mm.; fixed: B., 14 mm. 



24 Control larva. 4/14 to 5/28/18. Alive: Tot., 48 mm., B., 20 mm.; 

 fixed: Tot., 45 mm., B., 19 mm. 



25 Thyroidless larva. 4/14 to 5/20/18. Alive: Tot., 50 mm., B., 20 mm.; 

 fixed: Tot., 47 mm., B., 19 mm. 



26 Thyroidless larva. 4/15 to 10/13/17. Alive: Tot., 68 mm., B., 25 mm.; 

 fixed: Tot., 60 mm., B., 23 mm. 



27 Thyroidless larva. 4/28/17 to 5/7/18. Alive: Tot., 60 mm., B., 22 mm.; 

 fixed: Tot., 52 mm., B., 21 mm. 



Abbreviations and dates as in plate 2. 



56 



