484 MR. J. GRAHAM KBER ON [No7. 19, 



2. On the Male Genito-Urinary Organs of the Lepidosh'en 

 and Protopterus. By J. Graham Kerr. 



[Eeceived November 19, 1901.] 

 (Plates XXVII. & XXVIII.') 



(Text-figures 49-54.) 



There is nothing more needed in regard to the group of Dipnoan 

 Fishes than a correct and modern description of the male genital 

 organs, the current descriptions of these organs being either in- 

 complete or to a great extent erroneous. As some time must 

 elapse before I can deal with them in my detailed account of the 

 embryology of Lepidosiren, I have thought it worth while to write 

 out a short and concise account of the main features in this system 

 of organs in the two Dipnoans of which I have had specimens at 

 my disposal. I am the more moved to do so at this juncture, 

 because I feel that the conditions prevailing in the Dipnoans throw 

 an important light on the relations of the testis and its duct in 

 Polyptems as recently described independently by Jungersen and 

 Budgett. 



I propose, then, in this communication to give first a brief de- 

 scription of the conditions holding in Lepidosiren, then to summarize 

 the main points of difference found in Protopterus, and to conclude 

 by pointing out a general bearing which the facts mentioned may 

 be regarded as having. 



The only at all modern account of the male genital orgaus in 

 Lepidosiren is that contained in Ehlers's description of the viscera 

 pubhshed in the ' Gottiugen Nachrichten,' 1895. This account 

 I am able to confirm, from my own investigations, in some 

 important particulars, and also, to a certain extent, to amplify, 

 from my being in possession of males actually obtained duriiDg 

 the breeding-season. 



Lepidosiren. 



The testis proper in the mature Lepiidosiren is a very elongated 

 structure, rounded in section, and running in slight curves along a 

 great extent of the dorsal wall of the coelom just ventral to the 

 coal-black kidney. It is almost completely hidden away in a fat- 

 laden fold, which is developed to a special degree just before the 

 commencement of the dry season, and which has to be carefully 

 dissected away before the organ can be properly displayed. In 

 an adult male Lepidosiren (No. 666) measuring 719 mm. in total 

 length the testis proper, or, as I shall rather call it, the sperm- 

 producing portion of the testis (text-fig. 49 A, TJ, measm'ed 

 175 mm. in length by about 4 mm. in diameter. Anteriorly and 

 posteriorly this portion of the testis has a rounded end. From 

 the posterior end and from its inner aspect a flat tubular-looking 

 structure is continued backwards closely apposed to the surface of 

 the kidney, and so imbedded in dense connective tissue that it is 

 difiicult to make out its precise relations by mere dissection. This 



^ For explanation of the Plate, see p. 498. 



