34 ACALEPIIS IN GENERAL. Part I. 



tSars, iigaiii, speaks of tlieiii as jjartly coiifinaatory of his own, when, of {'oiu'se, the 

 earlier oljservation was the original one, and the later ones should lie considered 

 as confirmations. The Ijudding of the jiolypoid state of Stroljila had been known 

 to Dalyell for ^years Ijelbre it had even l)een noticed by Sars. Dalyell already 

 knew, in ISoG, what Sars was still ignorant of in 1S41, and, what seems hardly 

 to be generally known even now, though it is certainly true, that the base of the 

 Stroljila resumes the form of the original Scyphistoma after the Strobila lias dissolved 

 itself into free Ephyr*. 



But all these so-called "Hydra tuba" are not one and the same animal. They 

 are the early stages of development of the different kinds of covered-eyed Medusa3 

 which occur on the coast of Scotland, and the development of which presents similai' 

 phases. However, while Dalyell confounds in this manner the progeny of all the 

 Steganophthalms of the vicinity of Edinbin-gh, his very mistake shows the more 

 plainly how similar are the earlier stages of development of these different 

 species of Medusae. 



It is much to be regretted, that the facts so carefully and patiently traced by- 

 Sir John Dalyell, for so many successive years, should not have earlier attracted 

 the general attention of the investigators of Acalephs ; for his work contains satis- 

 factory information ujion many points, which were afterwards discussed as if no 

 obseiv.itions had yet Iteen made respecting them. Not less is it to be regretted, 

 that Sir John Dalyell Avas not more fidly acquainted with the investigations of Sars 

 anil of von Sie])old. Had he known their import, his own results would have been 

 much sooner incorporated into the history of these animals, while they Avould also 

 have acquired more precision and directness in his own mhid. As it happened, the 

 highly important labors of Dalyell have remained almost unnoticed until recently, 

 and have failed to exercise the intluence they might have had upon the progress 

 of science. 



N'arious i'acts bearing upon tlie phenomena of alternate generations had been 

 observed among Ilydroids by EJirenberg,' Loveu," Nordmann;' VanBeueden,^ and 



1 EiiUKNiuciii; (C. G.), Die Kurallciilliirre ilcs 1830, \ul. 0, \>. 701. This acoount is U>o ^liort 



rotlK'ii ^Ii,'crcs |ilivsiolijii;isi'li iiiitri>uclit inul sy>ti_'iiia- In In- at all sati>t'actiii-\-. 



tiscli vfrzcichnel. licrlin, 1S34. Ito. ■* VanI'.kn-khkx (!'. F.), M<Mnuirc siir Ics Cam- 



■■^ LoVEN (S. ],.). Jk'itra.Ll zur Kfiintiiiss drr |ianulaircs dc la role d'Ostciuk', considerees sous lu 



Gattuiig Campaiuilaj-ia uiid Syncoryiio, Wiegmann's ra])|iort pliysioldgiciiic, t'lnbryogcnique et zoologique ; 



Arcli. is;i7, vol. 1, p. -.'HI. Ann. Si-. Nat. 2e ser. 181;), vol. 20, p. S.W. i-t 



^ XuitDMAXN (Ai.. v.), Siir U'S cliangcnicnts que Jlcm. Ac. Unix. IS-l.j, vol. 17, Ito. tig. — Mcnioire 



I'ago ajiporte dans la niaiiii'ri- d'ctn- dt/s Caiiqiaim- sur rcinliryogynie ilrs Tiibiilaires, etc. jMeni. Acad, 



laires ; Coinptes-Rendus de I'Acad. des Sc. Pafis, V>vu\. 1844. 4tu. tig. 



