EXPLANATION OF PLATE XXX\ IL 



In all figures— 



AX. CART. = Axial cartilage 



B. CART. = Basal cartilage. 



D.F.C. — Dorsal Hii chambers. 



D.F.R. = Dorsal fin rays. 



M.P. CART. = Median paired cartilages. 



N.C. = Nerve cord. 



N.T. = Notochord. 



R.F. = Rostral fin. 



Fig. I. — Anterior end of A. aiisiniUs showing rostral fin and 

 notochord slighth raised. Drawn with the camera 

 lucida. 



Fig. 2. — -Outlines of .4. bassa)tnni and A. aiistralis to show 

 proportional widths. Drawn with the camera 

 lucida. Nat. sizes. 



Figs. 3, 4 and 5. — Bases of the cartilages of the mid-ventral 

 portion of the oral hood in three different specimens 

 of A. aitstyalis to show median \entral unpaired 

 tentacle. 



Figs. 6 and 7. — Fhe same in two other specimens with the 

 median ventral unpaired tentacle stunted. 



Figs. 8 to 12. — Bases of the cartilages of the miti-\ entral 

 portion of the oral hood in five different specimens 

 of A. hassauuni to show median paired tentacles. 



Figs. 13, 14 and 15. — Bases of the cartilages of the mid- 

 \ entral portion of the oral hood in three other speci- 

 mens of A. bassanuni showing median unpaired 

 tenta("le. 



Fig. 16. — Cartilages of oral cirri of .1. hassiDium showing 

 position of the median ventral pair. 



