1901.] 



LEPIDOSIREN AND PROTOPTEBUS. 



489 



It will be noticed in the specimen of which my drawing (see fig. 1, 

 Plate XXVII.) is a reconsti'uction, that the last two collecting-tubes 

 are relatively small. This was not a breeding specimen. In the 

 breeding male which was sectioned the posterior tubes, on the other 

 hand, were very large, much dilated with sperms, and the tubules 

 opening into them formed a special little mass projecting towards 

 the middle line and extending back in the connective-tissue sheath 

 which contains the hind end of the testis and the AVolffian duct 

 (T.^ in text-fig. 49). We have here an iiidication of the separating off 

 of a posterior specially genital region of the kidney comparable with 

 the familiar epididymis of" the anterior end of the mesonephros. 

 It is this posterior portion of the kidney which is seen in the re- 

 construction given in the figure now exhibited (see Plate XXVIII. 

 fig. 2, K^). In the non-breeding male it is much less conspicuous. 



Text-fig. 51. 



Section tbi'ough the Malpighian capsule of Lepidoslren. 



Section through the Malpighian capsule, into which a vas efferens opens, 

 showing spermatozoa in the cavity of the capsule. 



Spermatozoa first begin to appear in the kidney-duct of the 

 breeding male at a point about 7 mm. in front of the hind end of 

 the main testis. h\ front of this the lumen of the duct was, in the 

 breeding specimen examined, occluded for a distance of 12 mm. by 

 a plug composed of curious spherical saccular bodies. A few 

 spermatozoids had penetrated about halfway through this, but none 

 appeared to have got right through. From this plug backwards 

 the kidney-duct was packed full of sperms, and was rounded in 

 section, instead of flattened and collapsed as itwas further forwards. 

 The first open communication between the testis and the kidney 

 was found in this specimen about 12*5 mm. behind the end of the 

 sperm-forming testis, where a small tube (text-fig. 52, V.E.) was 

 seen to arise from the dorsal wall of the vesicular part of the 



