64 



Ich kiuui hin/Aitugeu, in einem Nest von Calotermes, welches ich 

 im April d. J. nur seiner Königin beraubte, den König mit einem Er- 

 satzweibcheu nebst vielen Eiern gefunden zu haben. 



Catania, 30. November 1887. 



2. The sucker on the Fin of Pterotrachea. 



By J. Walter F owk es, Cambridge, America. 



cingeg. 0. IJec. 18S7. 



Under the title »The sucker on the Fin of the Heteropods is not 

 a sexual characteristic« a note Avas published by me in the American 

 Naturalist February 1883, p. 20G) in which it was shown that the 

 female as well as the male Pterotrachea coronata Forsk., sometimes has 

 a sucker on the fin. This was published for the reason that text books 

 (Claus) and special works (Leuckart) on these Animals said that the 

 sucker was confined to the male Pterotrachea. 



Dr. J. Paneth two years later (Arch. f. Mikros. Anat. 1885, p. 233) 

 rediscovered that the female Pterotrachea sometimes has the sucker. 

 My note seems to have escaped him as he makes no mention of my 

 previous observation. 



Ur. C. Grobben (Arbeit. Zool. Instit. Wien, VII. p. 5, Separat) 

 refers to Dr. Paneths observation. He likewise seems not to know 

 that I had formerly discovered and published the fact that the female 

 Pterotrachea sometimes has the sucker on its fin. 



As these two excellent naturalists show in their writings that they 

 are not familiar with my note, it is safe to conclude that my discovery 

 may have escaped the attention of others. Although my note is a short 

 one I beliew it contains, a view of the homology of the sucker which 

 harmonizes with the results obtained five years after by Dr. G rob ben. 



Near the close of his paper Dr. Grobben says: »Als Resultat 

 dieser Untersuchung über die Morphologie des Heteropodenfußes er- 

 giebt sich, daß im Zusammenhange mit der pelagischen Lebensweise 

 und dem dieselbe ermöglichenden Auftreten eines Schwimmlappens 

 am Fußstamme, der söhlige Gastropod enfuß der Vorfahren sich zu 

 einem saugna])farti<>en Gebilde rückbildete, welches bei den Ptero- 

 tracheiden durch den Ausfall im weiblichen Geschlecht zu einem 

 secundären Geschlechtscharacter wurde.« 



In my note it is said of the sucker of the fin : »This organ is pro- 

 bably not confined to either sex in the above mentioned genera. Mor- 

 phologically it may be regarded as a functionless organ or the remnant 

 of a structure which in those Gasteropoda from Avhich the Heteropods 

 sprung was of great importance. The free-swimming habits which these 

 active mollusks have caused its reduction to a rudimentary organ.« 



