PART FOUR. 



THE EYES AND SUBNEURAL GLAND OF SALPA. 



BY MAYNARD M. METCALF, 

 Fellow of Johns Hopkins Univertity. 



WITH PLATES XLVII TO LVII. 



ACCEPTED AS A THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY THE BOARD OF UNIVERSITY STUDIES 



OF THE JOHNS HOPKINS UNIVERSITY, JUNE, 1893. 



