804 AELIS: 
EXPLANATION OF PLATE XXXVI. 
Fic. 60. Dorsal surface of mouth cavity and branchial chamber seen from 
below. The lower jaw, the lower half of the branchial arches, and the lower half 
of the oesophagus have been cut away. On the right side of the head the first 
branchial arch is pressed back slightly so as to show the ventral opening of the 
spiracular canal. X 1%. 
Fic. 61. Same as above, the skin and underlying tissues removed so as to 
expose the ventral surface, of the cranium and the ventral surfaces of the dorsal 
halves of the branchial arches. The efferent arteries and the pharyngeal and pre- 
trematic branches of the facialis, glossopharyngeus, and vagus nerves are seen. 
The pseudobranch on the right side of the head has been removed. X 1. 
