PLATE 50. 



ANTACEA. 



Fig. 1, 6, 8. Galeorhinus laevis (Page 176). P'ig. 2. Parmatuuus pilosus (Page 89). Fig. S 

 Triaenodon obesus (Page 163). Fig. 4. Carcharinus milberti (Page 133). Fig. 5, 11, 12. Triaki 

 SEMiFAsciATA (Pago 165). Fig. 7. Triakis henlei (Page 168). Fig. 9. Hemigaleus pectorali 

 (Page 150). Fig. 10. Eugaleus galeus (Page 153). Fig. 13-16. Scoliodon longurio (Page 114) 



The nictitating membrane in its early stages is merely a longitudinal fold in the lower eyelid, no 

 reaching the edges of the lid, fig. 1 and 2. This is the case in the very young of Galeorhinus laevis, fig. 1 

 in older specimens of this species the fold reaches the edge of the lid at one end, as in fig. 6, but in larg 

 ones the fold reaches the edge of the lid at both ends, fig. 8, and in transverse section its outlines resembl 

 those of Triakis, fig. 12. The membrane attains its greatest perfection and more nearly covers the eye 

 ball in the Cestraciontidae (Hammer Heads) and in the Carcharinidae, fig. 4, 13-16. In the Gale( 

 rhinidae it is better described as a fold instead of as a membrane. In all cases it is likely that onl 

 with some aid by muscular retraction of the ball can it be made to entirely cover the eye. Plate B 

 indicates some of the variations in the pupil of the eye. The oblique pupil of the Centraciontida 

 (Port Jackson Sharks) is shown on Plate 45, fig. 1. 



i 



