EXPLANATION OF PLATE XIX. 



Fig. I. — Ventral view of an embryo of T. kuhlii; only a few 

 of the gill- filaments are shown. 



2. — Dorsal view of an embryo of Hypolophus sephen ; the 

 yolk-sac, yolk-stalk and the branchial filaments are 

 not shown. 

 ,, 3. — Ventral view of a specimen of Pteroplatea poecilura. 

 A 3. 



,, 3(<*)- — Lateral view of the head of P. poecilura. 



,^ 4. — Ventral view of a specimen of Aetomylaeus nichofii. 



A 3. 



,, 4(a). — Lateral view of the head of A. nichofii to show 

 the characteristic shape of the spiracle. 



,, 5. — An egg-case of Chiloscy Ilium griseum. 



