LEPIDASTHENIA SIBOGAE. 163 



writes in his description of Iphione niuricata ') : „an dessus 

 de son (cirre dorsal) insertion, il existe un grand lobe 

 foliacé, frangé ; c'est le tubercule dorsal, ici particulièrement 

 développé, honiologue de Tólytrophore des segments 

 élytrigores." 



Darboux pleads for the homology of the elytrophore 

 and dorsal tnbercle, chiefly on account of the more median 

 situation of both organs, for he argues: „deux organes 

 homologues sont deux organes qui ont les mêmes connec- 

 tions." Now I think that this is only a part of the truth, 

 while the homology of two organs depends on their 

 agreement of anatomical characters (i. e. struct u re, f o r m, 

 position and connection), as well as on the simila- 

 rity of origin. Now, Hans Duncker ^) in his detailed 

 researches on the morphology of the Aphroditidae, based 

 upon the rich collections of the Museum of Göttingen, clearly 

 demonstrates, that there exists a great difference between 

 the anatomical structure of the dorsal tubercle and the 

 elytrophore, while the first named organ not only has the 

 muscular layer much less developed, but it totally lacks 

 the nerve. On the contrary the elytrophore and the 

 cirrophore quite agree, not only in the development of 

 the muscular layer but also in the presence of a nerve. 

 And with regard to the origin of both organs, Darboux 

 rightly quotes Hacker's sentence ■^) : „audi die Anlage der 

 Cirren und Elytren hat anfangs die Form von Knospen. 

 In einem alteren Stadium sehen wir dann die Rückencirren 

 und Elytren als liingliche, lappenförmige Gebilde, in einer 

 der Segmentzahl entsprechende Anzahl vorhanden. Noch 

 vor Erreichung des Nectochaeta-stadiunis erhalten die 

 siinimtliche Fussstummelanhange eine mehr flaschenförmige 

 Gestalt. Die genetische H o m o 1 o g i e der Elytren 



1) Annélides polychètes de la Mer rouge: Npuv. Arch, du Museum d'Hist. 

 nat. (se'r. 4) t. III, 1901, p. 229. 



2) Über die Ilomologie von Cirrus und Elytron bei deu Aphroditiden : 

 Zeitschr. f. wissensch. Zoölogie, Bd. LXXXI, 1906, p. 191. 



3) Die spütere Entwickluug der Polynoë-Larve: Zool. Jahrbücher, Abth. 

 f. Anatomie und Ontogenie, Bd. VIII, 1894, p. 253. 



Notes from the Leyclen IMuseum, Vol. XXXV. 



