MisceVaneovs. 481 



On HdclceVs Theory (Allceogenesis) of the Genetic Connexion hettveen 

 the Geryonidae and ^ginidse. By Alexander Agassiz. 



In the Proceedings of the Elliot Society for 1857 M'Crady gave 

 a very interesting account of the commensalism of the young brood 

 of a Cunina and of Turritopsis. No notice was taken of this re- 

 markable mode of development, M'Crady's observations having been 

 discredited by the later publication (1865) of a magnificently illus- 

 trated memoir on the " Riisselquallen " by Hiickel. The startling 

 hypothesis of the genetic connexion between the Geryonidae and 

 jEginidae contained in this memoir, and called by Hackel aUoeo- 

 genesis, has been ever since a stumblingblock to all theories of 

 genetic relationship among Medusae. 



Two short papers recently published — the one by Schulze (Mitt, 

 naturw. Ver. f. Steiermark, 1875, p. 125), and the other by Uljanin 

 (Ann. & Mag. Xat. Hist. March 1876, p. 215), have, however, proved 

 conclusively that Hackel's theory, like many other of his vagaries, 

 had no foundation of truth. It was based not merely on an incorrect 

 interpretation of facts, but the facts themselves existed only iu his 

 imagination. 



As, perhaps, with the exception of his monograph of the Radio- 

 laria, no other memoir has contributed more than the one above 

 quoted to give Hiickel the position he holds among zoologists, we 

 may be allowed to remind the Hiickelian school of naturalists that 

 this same genetic connexion has furnished the text for many a sermon 

 from their high priest. Infallible himself, he has been unsparing 

 in his condemnation of the ignorance and shallowness of his oppo- 

 nents. Proved now to be in the wrong, we expect therefore justice 

 without mercy from this stern scientific critic, and look forward in 

 the next number of the ' Jenaische Zeitschrift ' for a thorough casti- 

 gation of Hiickel by Hackel, showing up the absurdity of allceo- 

 genesis and all that hangs thereby. — SiUimans Amencan Journal, 

 May 1876. 



On the Embnjofjeny of the Ephemerae, especially that of Palingenia 

 \'irgo, Oliv. By M. N. Jolt. 



With the exception of the memoir by Luigi Calori " Sulla gene- 

 razione vi\'ipara della Chloe diptera (E, hemera diptera, Linn.)''*, 

 there is, so far as I know, no work on the embrj-ogeuy of the Ephe- 

 mercef. One might even say that all the acts concerned in the repro- 

 duction of these insects are still enveloped in a mysterious veil. 

 Their copulation has been differently described by the authors who 

 have treated of it. Swammerdain even denies that it ever takes 

 place, and thinks that the ova are fecundated by the male liquid 



* See ' Niiovi Annali delle Scienze Naturali,' ser. 2, tome ix. Bologua, 

 1848. 



[t The author seems to have no knowledge of Sir Jolm Lubbock's paper 

 "On the Development of Chlocon dimidiatum," in the Transactions of the 

 Linnean Society, vols. xxiv. and xxv. — Ed.] 



Ann. ff- Mnr/. N. ffisf. Ser. 4. Vol. xvii. 82 



