A DISTINCT GROUP. ' 5 



most valuable investigations into the Compound Ascidise, M. Edwards, without any knowledge 

 of the labours of Grant in the same field, not only demonstrated in a very complete manner 

 the anatomy of the Flustrse, but was the first to call attention to the close connection of their 

 structure with that of the Ascidiae, and the important bearing of this connection on their 

 systematic rank.* Cuvier had already determined a striking difference of structure between 

 the Sertularian Polypes and those of Alcyonium, and a third type of structure, widely different 

 from both, was now pointed out by M. Edwards as characterising the Flustrse and their 

 allies, which he proposed to distinguish under the name of " Polypes tuniciens." 



At the same time that the British and French zoologists were engaged in these interesting 

 discoveries, an accomplished and philosophic naturalist, Mr. J. V. Thompson, then officially 

 stationed at Cork as deputy-inspector-general of hospitals, was making a series of observations 

 on the marine productions of the coast. These observations had been commenced several 

 years before, and had already resulted in the celebrated discovery of the metamorphosis of the 

 Crustacea; it was not, however, until December, 1830, that they were given to the public. 

 In this year the author published tlie first number of a projected periodicalt which was to 

 contain a series of original memoirs on zoological subjects. Among the many important 

 papers contained in this publication was one " On Polyzoa, a new animal discovered as an 

 inhabitant of some Zoophytes." 



Thompson had examined the animals of BowerbanHa imbricata, Valkeria cuscuta, 

 V. jnistuhsa, Vesimlaria spinosa, and other allied forms, and the difference of their structure 

 from that of the Sertularise, with which they had been hitherto classed, struck him in its full 

 force. He traced the entire course of the alimentary canal, and made himself master of 

 almost every important point in their structure. He also perceived their close relation to 

 the compound Ascidise, and was the first to designate them by a distinct name which no 

 longer assumed their connection with the polypes. The name thus proposed by Thompson 

 for the group whose structure he had so well investigated was " Polyzoa." 



Residing in a remote part of Ireland, and in a great measure cut off from intercourse 



* Duiuortier and Van Beneden ('Hist. Nat. des Pol. comp. d'eau douce') assign to Lamouroux the 

 merit of having been the first to detect the affinity between the Polyzoa and tlie Ascidia;. Laraouroux's 

 views, however, upon this point are exceedingly vague and incorrect ; the difference between the 

 Polyzoa and the true radiate zoophytes never occurred to him, and he imagines tlie affinity with the 

 Mollusca to he possessed by the entire group of his polypes Ji polypiers. " J'ai dit," says he 

 (' Exposition Methodique des Genres de I'Ordre des Polypiers', Preface, p. vii), "que les polypes 'k 

 polypiers ne pouvaient en aucune maniere se comparer aux Hydras d'eaux douce, sous le rapport de 

 I'organisation ; qu'ils etaient plus voisins qu'on ne le pensait de la nombreuse famille des Mollusques, 

 et qu'avec le temps on en ferait peutetre une division de cette grande classe. Les nouvelles observations 

 que les circonstances m'ont permis de faire me confirment dans cette idee, et je ne doute plus que les 

 animaux des polypiers ne soient des etres aussi compliques dans leur organisation que les Mohusques 

 Ascidiens." He then goes on to compare the walls of the Ijody cavity in Goryonia, his, Alcijotiium, 

 &c., to the tunics of an Ascidian or the mantle of an ordinary Mollusc, a comparison which plainly 

 shows that he had no idea whatever of the relation in question. 



t ' Zoological Researches and Hlustrations.' By John V. Thompson. Cork, 1830. The date is 

 not printed on the title-page ; but is to be found on the paper wrapper in which the publication was 

 originally stitched. 



