PLATE 50. 



ANTACEA. 



Fig. 1, 6, 8. Galeorhinus LAEVis (Page 176). Fig. 2. Parmaturus pilosus (Page89). Fig. 3. 

 Triaenodon OBESus (Page 163). Fig. 4. Carcharinusmilbbrti (Page 133). Fig.5,11,12. Triakis 

 SEMiFA.sciATA (Page 165). Fig. 7. Triakis henlei (Page 16S). Fig. 9. Hemigaleus pectoralis 

 (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, not 

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

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

 ones the fold reaches the edge of the lid at both ends. fig. 8, and in tran.sverse section its outlines resemble 

 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 Galeo- 

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

 with some aid by muscular retraction of the ball can it be made to entirely cover the eye. Plate 50 

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

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



