studies on iiiuriiif> Ostraeods 59 



genital papUki as a penis, as A. GAKbIM has done; the copulatory organs might have conveniently 

 been called „genital limbs" or something similar. We know, however, that this is not the case. 

 On the contrary, in other groups* the distal parts of the ducts of the sexual organs do not emerge 

 between the copulatory appendages, but more or less distally on them; in other words the 

 latter are to be taken as real penes. 



The question now arises: are the copulatory organs in the Cypridinids homologous 

 to the same organs in other Ostraeods. It is exceedingly difficult to answer this question; 

 a multitude of facts from comparative morphology and embryology, which unfortunately I 

 f-annot yet give, are necessary for this answer. G. W. MtJLLER does not attempt to give any 

 definite answer to this question. He writes, 1894, p. 77: „. . . . So beschranke ich mich hier 

 darauf, die verschiedenen Moglichkeiten der Homologisirung des Penis, die ich kenne, aufzu- 

 ziihlen, ohne damit behaupten zu woUen, daB damit alle Moglichkeiten erschopft sind. — 



1 ) Der Penis der C y p r i d i n i d e n ist das umgewandelte 8. GliedmaaBenpaar und dem 

 Inirstenformigen Organ der Podocopa, nicht aber dem Penis der iibrigen Ostracoden 

 (einschlieUlich der Podocopa) homolog. Der Penis der letzteren ist nicht aus einem GliedmaaBen- 

 paar hervorgegangen. Hierfiir lieBe sich das verschiedene Verhalten des Penis bei den 

 C y p r i d i n i d e n und den iibrigen Ostracoden anfiihren. Bei den C y p r i d i n i d e n 

 nimmt er keinen Theil des Vas deferens auf, sondern steht nur neben der Miindimg. Bei den 

 iibrigen Ostracoden umfaBt er den Endtheil des Vas deferens, ist selbst Begattungsrohr. 



2) Der Penis der Cypridiniden ist aus einem GliedmaaBenpaare hervorgegangen, das sicli 

 bei den Podocopa gespalten und den Penis nebst dem biirstenformigen Organ geliefert hat, 

 wiihrend bei den H a 1 o c y p r i d e n und P o 1 y c o p i d e n nur die eine Halfte erhalten ist. 



3) Der Penis der Cypridiniden ist aus 2 Gliedmaafienpaaren hervorgegangen, von denen 

 das eine den Penis der H a 1 o c y p r i d e n, P o 1 y c o p i d e n und Podocopa, das andere das 

 biirstenformige Organ der Podocopa geliefert hat. — Ich finde keine Griinde, welche die eine 

 Amiahme wahrscheinlicher machen, als die andere." As for several reasons I am fuUy convinced 

 that the copulative organs are homologous formations in the whcjle Ostracod group — I regard the 

 conditions in the Cypridinids as primitive — it seemed to me best to use the term penes 

 for these organs, thereby following the terminology accepted by most previous investigators. 



It will be necessary in the future to define and amplify the special terminology for this 

 organ very considerably. The reason why this is not done here is that in the present work this 

 organ is dealt with very superficially. The complicated structure of this organ needs a very 

 thorough and comprehensive examination, a piece of work that probably needs a special treatise. 



Gills: — 



I shall only mention in passing A. DOHHN's hypothesis (Geschichte des Krebs- 

 s t a m m 6 s) that the gills in the genus Asterope are homologous with epipodial appendages of limbs, 

 the other parts of which have now entirely disappeared. No proof of this assumption can be 

 given, but it also seems, at least at present, impossible entirely to disprove it. It may, however, 

 be pointed out that it seems much more probable that we are only concerned with accessory folds 

 of the skin without any connection originally with limbs; (on the other hand it is quite uncertain 



• The state of affairs in Polycopidae is unfortunately not known with curlainly. 



