Chap. I. HISTORY OF THE ACALEPHS. 33 



founded the history of at least two different genera ; for I have no doubt, that, 

 while the Hydra tuba, represented by him in his great Avork on " Eare and Remark- 

 able Animals of Scotland," Vol. I, PL XIII., is the offspring of Aurelia aurita, the 

 forms Avhich he represents imder the same name, PL XIV., are the offspring of 

 Chrysaora, and those of PL XIX. are perhaps derived from Cyanea capillata. 



In 1834, John Graham DalyelP (afterwards Sir Jolni) describes, under the name 

 of Hydra tuba, an animal which is identical with Sars's Scyjjhistoma, already men- 

 tioned and figured hy the latter in his paper of LS2U ; ):)ut Dalyell mentions many 

 particulars, which seem to have for a long time remained unknown to other natu- 

 ralists. He says that this animal is very voracious, and that it multiplies by 

 budding, the buds remaining united to the base of the parent ))y a ligament, 

 until this is rujstured as the emlnyo withdraws to establish itself independently. 

 A single specimen had eighty-three descendants in thirteen months. Sars did not 

 observe the budding before the year 1836/ and he did not see the Ijuds separate 

 and grow independently, as Dalyell did, and as I have done myself. In a subse- 

 quent paper,^ Dalyell describes his further experiments with Hydra tuba up to 183G. 

 He kept a colony of these animals alive, Avith their descendants, during six vears, 

 and numbers attained maturity. They fed rapaciouslj-, grew and bred successive 

 generations at all seasons of the year. In February and March he ol)served a 

 pendulous flexible prolongation, of an inverted conical form, on the face or disk of 

 some of these Hydras (the Strobila of Sars), developing gradually into twenty or 

 thirty successive strata, broadening outwards, which, when more mature, Avere liber- 

 ated, and swam at large in the Avater (the Ephyroid Medusa of Sars). He also 

 considers them as Medusari*, and gives good figures of one of them, figs. 2 and 

 3, p. 94. Later authors have failed to do justice to Sir John Dalyell. Speaking 

 of his observations of the year 1836, Wiegmann, for instance, says,^ that they 

 contain so much that is enigmatical, that they require to be repeated and explained 

 by other naturalists. Surely his OAvn ignorance of the fixcts observed by Dalyell, 

 the accuracy of Avhich has been fully borne out, did not justify such a rel)uke. 



'■ On the Propagation of .Scottish Zuiiphytes, - Wiegmann's Arcliiv, 1841, vol. 1, j). 24. 



Edinb. New Philos. Journ. 1834, vol. 17, page 411, » Fni-ther Illustrations of the Propagation of 



and Report British Association for Adv. of Sci- Scottish Zoiiiihyfes, Edinburgh New Philosophical 



ence, 1834, p. 598. An abstract appeared in Fro- Journal, 183(;, vol. 21, p. 88 ; fully translated into 



riep's Notizen. The name of Dalyell is misspelled German in Froriop's Notizen, vol. 50, No. G, and 



in the Edinburgh New Philosophical Journal, and in abstract in Wiegmann's Archiv, 1837, vol. 2, p. 



stands as Dalzell ; under which name the author 278. The Isis of 1838 contains also abstracts of 



became known in Germany, and is quoted again Dalycll's papers. 



and again in Wiegmann's Arch, for 1834, vol. 1, ■' Archiv, fiir Naturgeschichte 1837, 2d vol. 



p. 303 and 305, and for 1837, vol. 2, p. 192. p. 278. 

 VOL. ni. 5 



