HISTORY. 69 



name of Firdericella, called in honour of Frederic Cuvier, and he gives a tolerahly extensive 

 synonymy of the species of fresh-water Polyzoa, which he distributes under the five genera, 

 Cristatclla, Alct/onella, PlumatcUa, PahidiceUa, and Fredericella ; he, however, still maintains 

 the generic identity of Lophopiis and Plumatella. He divides the whole, as he had done in 

 his previous paper, into two sub-classes, Poli/jnaria hippocrepia and P. infundihulata. 



In the first volume of the Supplement to the ' Dictionnaire des Sciences Naturelles,' 

 published in 1840, M. Gervais, in the article Alcyonella, again gives us the result of his 

 researches into this subject ; he still rejects the generic distinctness of LopJwpus, and even 

 views Alcyonella and Plumatella as mere species of the same generic form. 



In 1841, M. Coste read to the Academic des Sciences a paper on the organization of the 

 fresh-water Polyzoa ; * though unaccompanied by figures, M. Coste's memoir gives a very 

 good account of most of the important points in the anatomy of the hippocrepian Polyzoa ; it 

 describes the muscular, digestive, and nervous systems with much exactness and with con- 

 siderable detail ; and maintains the expediency of removing the Polyzoa out of the Radiata, 

 and dlacing them among the Mollusca. 



A few months later, M. Coste addressed to the Academic a short note on the " Tubulaire 

 sultane " [Ffedericella sultana),^ in which he announces that the organization of this Poylzoon 

 is in general c[uite conformable to that of the hippocrepian species described in his former 

 communication. 



In the year 1842, MM. Dumortier and Van Beneden read, before the Royal Academy 

 of Brussels, the first of a series of papers, which these naturalists proposed presenting con- 

 jointly, on 'the Compound Polypes of fresh water. "ij: This memoir consists entirely of a 

 historical introduction to the subject ; it is most elaborate and learned, and I have derived 

 much assistance from it in drawing up the present historical outline. 



In 1843, I read to the Royal Irish Academy a memoir 'On the Muscular System 

 of Paludicella and other Ascidian Zoophytes of fresh water.'§ The paper is chiefly 

 occupied with the description of the muscles of Paludicella. They are divided into three 

 groups — one belonging to the alimentary canal, one to the tentacular sheath, and one to the 

 walls of the cell. Being then an inexperienced observer, and possessing but an imperfect 

 microscope, I was unable to pursue the anatomy of the animal as far as could be desired, and 

 several interesting points of structure escaped me at the time. The retractor muscles of the 

 alimentary canal in Plumatella repens, and the radiating muscles of its sheath, are also 

 described in this memoir, though I then overlooked the fact that the latter are divisible 

 into an anterior and a posterior set ; while Dr. A. Farre's account of the action of certain 

 muscles in the Polyzoa is examined, and an attempt made to explain such action in a manner 

 somewhat different from the views entertained by this anatomist. 



* Coste, Propositions sur Torganisation des polypes fluviatiles. ' Comptes Rendus,' 1841. 



f Coste, Observation relative S, la Tubulaire sultane. ' Comptes Rendus,' 1841. 



\ Dumortier et Van Beneden, Histoire Naturelle des Polypes composes d'eau douce. 'Nou- 

 veaux Memoires de I'Acad. Roy. de Bruxelles,' t. xvi. 



§ Allman, On the Muscular System of Paludicella and other Ascidiau Zoophytes of fresh water. 

 ' Proc. Rov. Irish Acad.' 1843. 



