324 ME, J. S. BTJDGETT ON SOME POINTS IN 



II. The Male Organs. 



The following observations have been made on adult male specimens of Polypterus 

 senegalus and P. lapradei taken at the commencement of the breeding-season. Series 

 of the urinogenital organs of the young P. senegalus, 13 cm. and 9 cm. in length, have 

 also been carefully studied. 



In the adult male a ridge of testicular tubules extends the entire length of the body, 

 lying parallel to and directly over the kidney on either side (PL L. figs. 2, 3, t.r.). Each 

 testis-ridge is enlarged towards its anterior end, forming a conspicuous lobulated testis 

 (fig. 3, t.) : that on the left side is situated more anteriorly than that on the right. 



The testis and testis-ridge are covered by peritoneum, the two folds of which are 

 approximated at the base of the testis to form a mesorchium, in which spermatic veins 

 pass to the cardinals (fig. 3, sp.v.). 



The tubules of the testis and testis-ridge open by very numerous short ducts into a 

 longitudinal canal extending the whole length of the gland lying in the mesorchium at 

 the base of the testis, and further back between the testis-ridge and the kidney (PL L. 

 fig. 3, t.d. ; PL LI. figs. 10, 11, t.d.). Posteriorly this duct leaves the testis-ridge 

 as the vas deferens (PL L. figs. 5, 6, v.d.), and passing backwards in the same sheath of 

 connective-tissue as the ureter, opens upon a papilla into the narrow neck of the urino- 

 genital sinus just before it opens to the exterior (PL L. fig. 5 ; PL LI. figs. 12, 14, g.ap.). 



This duct is of even calibre throughout the greater part of its length, but is 

 somewhat dilated in the region of the lobulated testis. 



The tubules of the adult ripe testis are very numerous, and dilated with spermatozoa 

 and what appear to be sperm mother-cells. The tubules are embedded in lymphoid 

 tissue with deeply-staining nuclei (PL LI. fig. 10, t.). The spermatozoa are very small, 

 about the diameter of a red corpuscle in length, thickened anteriorly and tapered 

 posteriorly (PL LI. fig. 13). 



The arrangement of the tubules of the testis-ridge is a simplification of that of the 

 testis-tubules. Here three or four longitudinal tubules are connected by numerous 

 transverse tubules with the testis-cluct (PL LI. fig. 15, t.r.tbs.). The walls of these 

 tubules are lined with columnar epithelium, and are not surrounded by lymphoid 

 tissue as are the tubules of the testis, but by dense connective-tissue. 



The tubules of this testis-ridge do not appear to be functional testis-tubules, 

 although amongst them were found what appeared to be traces of spermatozoa. 

 It seems possible that the tubules of this ridge assist in carrying away the sperm from 

 the testis to the vas deferens, but do not themselves actually produce spermatozoa. 



In the young Polypterus senegalus, 13 cm. in length, the tubules of the testis which 

 are embedded in lymphoid tissue are lined by a single layer of large-celled columnar 

 epithelium, while the lumina are small (PL LI. fig. 16, t.tbs.). The tubules of the testis- 

 ridge differ little from those of the adult male (PL LI. figs. 15, 17, t.r.tbs.) ; the tubules, 



