1901.] LKPIDOSIREX AND PUO'JL'OI'TEKlN. 496 



1 start from the standpoint of one who believes that the 

 two great products of the ccelomic lining (i. e. the genital and the 

 excretory products) made their way originally to the exterior by 

 the same mode of exit — by the nephridial openings ', and that 

 the general course of subsequent evolution has probably as regards 

 the genital products been such as to keep or make their mode of 

 exit as direct and simple as possible, rather than such as to make 

 their exit more and more complicated and difficult as some 

 zoologists would have us believe. 



The condition in Lepidosteus or Acipemer may be looked upon 

 as relatively primitive amongst fishes. Here testis and kidney are 

 alike elongated and vasa efferentia pass off along the whole length 

 of the testis to the greater part of the length of the kidney. 



In Lepidosiren, as above described, the testis has become divided 

 into two regions, a formative and a vesicular, and the connection 

 between testis and kidney has become restricted to the posterior 

 portion of the vesicular region. 



In Protopterus we find again the division of the testis into 

 formative and vesicular regions, but now the communication of 

 testis-cavity with kidney is still further restricted to the extreme 

 hind end of the testis. 



This, it seems to me, is but a step from what has been described 

 for adult Crossopferygians, where again we find a division of the 

 testis into a formative and a conducting region, the latter 

 communicating at its extreme hinder end with the kidney-duet. 

 no longer, however, through complicated kidney-tubules but by a 

 simple direct opening 2 . 



Finally, as Jungersen has well pointed out and has been shown 

 in resume above, the Teleoslean condition is naturally derivable 

 from that in Polypterus. 



.According to the facts and views expressed in this paper 3 , the 

 genital ducts of male Ganoids, Dipnoans, Crossopterygians, and 

 Teleosts would fall into some such scheme as that expressed in 

 the accompanying rough diagram (p. 49ii). 



In conclusion, it is only fair to state that while the facts 

 described above are in great part new, the morphological hypothesis 

 which they are held to support was suggested long ago by Semon ' 



1 Budgett is led by his studies on Polvpterus to believe that the arrangement 



there is a primitive one, and to side with those who believe thai th nnection 



between gonad and kidney is secondary. Trans. Zool. Soc. vol. iv. ]>. 330. 



'-' Exactly as has apparently come about in Discoglot ut amongst anurous 

 Amphibians— the surviving connection being, however, in this latter 

 anterior instead of posterior. 



3 It will be seen that this view of the morphology of the Teleosteau male 

 genital duct differs in some essential particulars from that of Jungersen 

 lie points out that in Lepidostetu and Acipenaer the testicular network opens 



into the Ifalpigbian capsules, in Amia into the tubule below tl apsule 



,t into the kidney-dud direct, fn Amm. as i ipared with Lepidosteus and 



Acipetuer, the openings ot the testicular network into the kidney-system maj 

 be regarded as having migrated don n the tubule in the direct ion ut' the external 



opening. Let such migratioi itinue until thej opened close to the exterior, 



and a condition resembling that "i Teleosts would be reached (Zool. Lns. 

 Bd. win. p. 332, I 



Baup a i Urogenitalsystems der Wirbelthiere : Jena, 1891 



