Plate 11. 



Figs. 52-57. Halosaurus radiatus Garman. 



Fig. 52. The fish seen from the side. Drawing; natural size. 



Fi'''. 53. Radiating cephalic disc in transmitted light. Photograph; magnified 1 : 17. b', 

 large blood vessel leading to the disc ; n, main disc nerve ; n', smaller ac- 

 cessory disc nerves. 



Fig. 54. Radiating cephalic disc in transmitted light. Photograph; magnified 1 : 41. b', 

 large blood vessels leading to the disc ; n, main disc nerve ; u', smaller ac- 

 cessory disc nerves. 



Fig. 55. Radiating cephalic disc in transmitted light. Photograph; magnified 1 : 17. b', 

 large blood vessel leading to the disc ; n, main disc nerve ; n', smaller ac- 

 cessory disc nerves. 



Fig. 56. Transverse section through a cephalic radiating disc along its longer axis. Stained : 

 haematoxylin-picric acid-fnchsin. Drawing ; magnified 1 : 42. b, close capillary 

 network of blood vessels underlying the cylinder cell layer ; b', large blood vessel 

 leading to the disc ; c, thickened connective tissue of the inner wall of the slime 

 canal on which the cylinder cell layer rests; cv, cavity of slime canal; d, cyl- 

 indrical cells of the radiating disc; m, marginal zone of the radiating disc; n, 

 main disc nerve; s, outer wall of slime canal. 



Fig. 57. Part of a transverse section through the cylinder cell layer of a ccjjhalic radiating 

 disc. Stained: haemotoxylin-picric acid-fuchsin. Drawing ; magnified 1 : 200. 



b, close capillary network of blood vessels underlying the cylinder cell layer: 



c, thickened connective tissue of the inner wall of the slime canal on which the 

 cylinder cell layer rests ; d, cylindrical cells of the radiating discs. 



