1901.] LEPLUOSIREN AND PEOTOPTEBUS. 493 



coaly-black pigment, which is so characteristic of the rest of the 

 kidney. The epididymes of the two sides are completely fused 

 in the middle line, as is shown by the reconstruction in Plate 

 XXVIIl. fig. 3, where also it is seen that thei-e is no ci-ossing of 

 collecting-tubes across the median plane. That the posterior 

 epididymis is really the posterior end of the kidneys is shown by 

 the exaaiination of young stages. In male specimens of Protopterus 

 of 90 mm. in lengtli I find the posterior ends of the kidneys fused, 

 but not differing in structure from the remainder of the organ. 



Testicular netivorlc. — As in Lepidosiren, there are distinct remains 

 of a testicular network, only here it is reduced still further, being- 

 represented merely by communications between testis and kidney 

 at the extreme hind end of the testis. 



From the hind end of the united vesicular portions of the testes 

 a sinus passes dorsalwards on each side through the substance of 

 the epididymis. Here it becomes very irregular in shape, sending 

 out various irregular projections and line prolongations which 

 communicate with the kidney-tubules. Each of the large sinuses 

 mentioned must be looked upon as a large vas efferens, the last of 

 the series. 



The cavities of the vas efferens and its prolongations as well as 

 those of the large collecting- tubes in the epipdidymis are in 

 breeding males packed with spermatozoa. 



I have not, so far, been able to make out glomeruli in any of the 

 sperm-containing cavities in Frotoptenis, and it is possible that 

 here, as in the case of Rana fusca, they have degenerated in the 

 Malpighian capsules connected with the testis. The spex-matozoa 

 reach the kidney-duct by the last few main collecting-tubes (three 

 in a breeding specimen examined). 



MvMerian ducts. — In the adult male the posterior portion of the 

 Miillerian duct persists as well as the coelomic funnel (c/. text- 

 fig. 53 B, M.D.). The two ducts unite posteriorly, and then end 

 blindly within the base of the urogenital papilla. I can find no 

 patent communication with the vesicular region of the testis such 

 as Parker describes. 



Ceeatodtjs. 



I have unfortunately not had any adult specimens of Ceratodus 

 at my disposal. But there can be little doubt from Giinther's 

 description, and from Semon's statement that he has found sper- 

 matozoa in the Malpighian capsules, that the conditions here are 

 similar in all essentials to what I have described in the other 

 two Dipnoans. The " vasa deferentia " described by Griinther are 

 pretty clearly the Miillerian ducts, which retain their embryonic 

 condition even more clearly in Gercttodus than in Pi'Otop)terus, 

 remaining in the adult with patent lumen along their whole 

 length. 



The fact that there exists in Lepidosireu and Frotojiterus a defi- 

 nitely developed testicular network connecting the testis and kidney 

 must be held, I think, to constitute weighty evidence in favour 



Pkoc. Zool. Soc.~1901, Vol. II. No. XXXIII. 33 



