6S HISTORY. 



to do with the Polyzoa. There can be little doubt that they are the fossil sporangia of certain 

 DesmidiecE. 



In the ' Transactions of the Philosophical and Literary Society of Leeds,' 1837, we have a 

 paper by Mr. Teale, on AlcjjoncUa stagnamm.* The author gives a good account of the 

 habits and external characters of the animal ; but he informs us of no new fact concerning its 

 anatomy. 



In 1838, Johnston published the first edition of his excellent ' History of British 

 Zoophytes ; 'f in the account, however, here given of the fresh-water Polyzoa, this author 

 merely follows his predecessors. He distributes the species under the three genera of CristateUa, 

 Alcyonella, and PJumatella ; he makes the " Polype a Panache " merely one of the varieties of 

 Alcyonella stagnorum, and, led astray by the erroneous synonymy of previous authors, he 

 enumerates the Phimatella gelatinosa of Fleming's " British Animals " as a species with circular 

 disc, distinct from Blumenbach's Tnhdaria sidtana. 



In the ' Bulletins de FAcademie Royale de Bruxelles ' of the following year, M. Van 

 Beneden published a note, containing observations on some of the fresh-water Polyzoa. J 

 Nordmann had just indicated the existence of male and female individuals existing separately 

 in Tcndra zostericola, a marine Polyzoon,§ and M. Van Beneden now makes a similar state- 

 ment with respect to AJcyonella. \\ He describes also a circulation of fluid in various parts of 

 the body, and he supposes it due to the action of cilia, which he affirms to exist on the exterior 

 of the alimentary canal as well as on the skin. This motion of the fluid in the interior had 

 been, as we have seen, already noticed by Trembley ; and M. Van Beneden now for the first 

 time refers it to its true cause by showing its dependence on vibratile cilia, though he incor- 

 rectly describes the external surface of the alimentary canal as ciliated. He believes he has 

 seen at the base of each tentacle an aperture, which he regards as an aquiferous mouth 

 ("bouche aquifere "), destined to give admission to the external water; though in a subse- 

 quent memoir he admits that this appearance is deceptive. He describes the great supra- 

 oesophageal ganglion, and mentions the existence of locomotive ciliated embryos in Alci/onella. 

 He mentions having found, along with M. Gervais, the FredericcUa ar\d PaJudicella ; and in 

 fine he shows how the form of Alcyonella is varied by accidental circumstances influencing 

 its growth. 



In the same year, M. Gervais published, in the ' Annales Francaises et Etrangeres 

 d'Anatomie,' a valuable paper on the fresh-water Polyzoa.^ This memoir, which is an 

 extension of his previous one, is of more importance in a zoographical than in an anatomical 

 point of view. For Blumenbach's Tiibularia sultana, he institutes a new genus under the 



* Teale, On Alajonel/a stagnanim. 'Trans. Phil. Soc. of Leeds,' i, p. 116. 



t Johnston, 'History of the British Zoophytes.' Edinburgh, 1838. 



X Van Beneden, Qnelques Observations sur les Polypes d'eau douce. 'Bull. Acad. Brux.,' 1839. 



§ Nordmann, Recherclies microscopiques sur I'anatomie et le developpenient du Tendra zostericola. 

 'Ann. Sci. Nat.,' 2' ser., xi. 



II With Van Beueden's statement of the separation of the sexes in Alcyonella, my own observa- 

 tions do not agree. See above, p. 32. 



1[ Gervais, Observations sur les Polypes d'eau douce. 'Annales Pran9aises et Etrangeres 

 d'Anatomie,' 1839. 



