336 ME. J. S. BUDGETT ON SOME POINTS IN 



smallness in size of the anal-fin muscle. The rectum has been partially cut 

 away and the ventral wall of the urinogenital sinus removed. 



Fig. 5. A similar view of the urinogenital sinus in the male (pp. 324, 331), showing 

 the genital aperture, the narrow neck of the urinogenital sinus, the great 

 width of the base of the anal fin and the great development of its muscle. 



Fig. 6. View from the right side of the urinogenital sinus in a large male (p. 324), 

 the anal fin and its muscle, showing the course of the vas deferens ; these 

 organs, together with the rectum, having been dissected from the body. 



Fig. 7. View from below of the anal region in a female (pp. 328, 330), showing the 

 slit-like urinogenital aperture and the abdominal pores. 



Fig. 8. A similar view in a male (pp. 328, 330), showing the wide urinogenital aperture. 



Fig. 9. A vertical section of a very young female Polypterus senegalus, 9 cm. in length 

 (p. 330), passing through the abdominal pores, showing a thin nucleated 

 diaphragm closing the abdominal pores, at the same time showing an 

 exudation of the ccelomic fluid. The caudal vein and abdominal vein are 

 cut through just anterior to their junction. 



PLATE LI. 



Fig. 10. A vertical section through the testis and kidney of an adult male (pp. 324, 

 327, 328). The ureter is injected blue. The testis-tubules are shown opening 

 into the testis-duct, and a kidney-ductule opening into the ureter. The 

 magnification is 6 diameters. 



Fig. 11. A similar section behind the testis (pp. 324, 327, 328), showing the relation 

 of the testis-ridge and duct to the ureter in an adult male. 



Fig. 12. A similar section in the region of the urinogenital sinus (pp. 324, 328), showing 

 the duct of the testis opening upon a papilla into the urinogenital sinus. 



Fig. 13. Spermatozoa compared with a blood-corpuscle (pp. 324, 331). Zeiss ocular 3, 

 objective E. 



Fig. 14. An enlarged drawing of the right half of fig. 12 (pp. 324, 325), showing the 

 stout columnar epithelial lining of the vas deferens. 



Figs. 14 to 24 are all magnified about 70 diameters. 



Fig. 15. An enlarged drawing of the testis-ridge of fig. 11 (p. 324), showing the similar 

 appearance of the ductules of the ridge and the main testis-duct. They 

 are lined by a large-celled epithelium and embedded in connective-tissue 

 with a few small blood-vessels. 



Fig. 16. A vertical section through the kidney and testis of a young male P. senegalus, 

 13 cm. in length (pp. 324, 327, 328), showing the minute structure of the 

 testis. The tubules are lined by large glandular cells, and are embedded 

 in lymphoid tissue similar in appearance to the lymphoid tissue of the 



