PLATE 2 



EXPLANATION OF FIGURES 



22 Ventral view of a wax reconstruction of the thyreoid ghmd of an Acanthias 

 embrj'o 36 mm. long (No. 42). The anterior rhomboidal corpus and the posterior 

 elongated cauda are easily recognizable. The dark area on the corpus represents 

 the position of the intraglandular cavity whose outline has been projected on the 

 ventral surface of the gland. This cavity has opened to the outside on the dorsal 

 aspect of the gland. Its opening is not indicated in the figure. X 100. 



23 Ventral view of a wax reconstruction of the thyreoid gland of an Acanthias 

 embryo 60 mm. long (No. 47). The roughness on the surface is due to the begin- 

 ning formation of follicles in the epithelial plates. The clear areas represent 

 perforations or fenestrae in the plates produced by the gradual separation of the 

 forming follicles. The points at which the intraglandular cavities have opened 

 to the outside are also seen. X 65. 



222 



