8 Prof. R. Kossmann on the CrjptoniscidiB. 



with absolute certainty as a retrograded testis. This gland 

 was discovered by Buclihok* in Cryptothir halani, but is 

 wanting in none of the Cryptoniscidge examined by me, while 

 no female Bopyrid or Entoniscid possesses even the smallest 

 trace of it. 13uchholz thought that this gland was to be re- 

 garded as an accessory organ of the sexual parts ; notwith- 

 standing repeated endeavours he could discover no efferent 

 ductj but he found the granulated contents to be like those of 

 the terminal section of the female genital duct. His figure 

 and description represent the organ as a thin cord inflated 

 in three places, situated on three sides above and outside of 

 the ovaries, and filled with a finely granular substance. The 

 inflated parts form cellular diverticula. 



Now this organ extends through the last three segments of 

 the pereion, therefore the same in which the testis is situated 

 in the male. These three segments of the larva are widely 

 separated immediately before tlie last change of skin, and 

 afterwards enormously enlarged by colossal reception of 

 nutriment. At the same time, however, the triple division 

 continues recognizable by transverse constrictions. If there- 

 fore a testis no longer in function be present, what is more 

 natural than that this should retain its original thickness in 

 the three segments, but become stretched into a thin cord in 

 the intervals — in short, acquire the form represented by Buch- 

 holz ? and is not also the deflciency of the efferent duct, ascer- 

 tained by me, in favour of the view that we have to do with 

 an organ no longer in function ? Lastly, as regards the con- 

 tents. In my transverse sections these appear as a finely 

 granular, strongly refractive, and very strongly colouring- 

 detritus, which in these three properties is absolutely similar 

 to the contents of the testes in the males of the Bopyridae 

 (provided there is no semen in them). 



From all this we may regard it as almost proved to demon- 

 stration that the CryptoniscidjB are really protandrous herm- 

 aphrodites, in which the testis attains its maturity in the 

 final larval stage, and is then visible in the mature female as 

 a rudimentary organ without an efferent duct. 



The question now arises, what circumstances have operated 

 for the production of this kind of hermaphrodism, seeing that 

 the Bopyridge, which are so nearly allied, are certainly not 

 hermaphrodites ? 



We generally find hermaphrodism especially in slow-moving 

 or adherent animals, and to these it gives an essential advan- 

 tage in the struggle for existence. In the first place, it renders 



* Bucbholz, loc. cit. p. 316, Taf. xvi. figs. 2 & 3, G. 



