204 DB. T. S. COBBOLD ON DISTOMA CLATATTJM. 



In the year 1835, Professor Owen commnuieated to the Zoolo- 

 gical Society the anatomical memoir to which I have already 

 made reference. In his paper he ably discusses several questions 

 relating to the structure of Distoma clavatiim, and throws con- 

 siderable light npon the organization of this species. He quotes 

 the previous writings of Pallas, Eudolphi, andMenzies, and estab- 

 lishes the identity of Fasciola ventricosa and F. clavata. Although 

 some particulars are wanting respecting the precise mode of ter- 

 mination of the digestive tubes, I think that there can be no 

 doubt as to the propriety of retaining this species amongst the 

 true Distomes. I believe that the large "lateral cavities" de- 

 scribed by Professor Owen are neither more nor less than the 

 somewhat unusually distended alimentary cgeca. In this parti- 

 cular every helminthologist is familiar with the varieties presented 

 by different species of Trematoda. At all events, there is here 

 no good ground for retaining the generic name Fasciola ; and still 

 less are we called upon to recognize any of the forms under the 

 title of Ilirudinella, although Garsin first described the species 

 binder this generic title. 



In 1845, Dujardin placed the worm with the true Distomes, 

 yet at the same time expressed grave doubts as to whether it 

 were, in any sense, a fluke. " Ce ver," he remarks, "n'est cer- 

 tainement pas un distome ni meme un trematode. Si sa forme 

 exterieure et ses deux oscules lui donuent quelque ressemblance 

 avec les distomes, sa structure musculeuse le rapproche davan- 

 tage des Grordius, et son tegument ressemble a celui des siponcles." 

 M. Dujardin carefully examined the specimens preserved in the 

 Paris Museum ; and with regard to one particular example, de- 

 scribed as " Pasciola, troxive dans la mer de Nice," be says, it 

 presents " une certaine analogic avec le pretendu Distoma cla- 

 vatiim.'''' Manifestly Dujardin himself was somewhat puzzled by 

 the resemblances in question. He does not appear to have had 

 any opportunity of examining fresh specimens ; yet he mentions 

 the species as tolerably common in the Bonito, being also occa- 

 sionally present in the Tunny. At all events it would appear by 

 evidence derived from various sources, that the rightly so-called 

 Distoma clavatum is not unfrequently taken from the ocean quite 

 independent of its piscine "bearers." 



In reviewing the foregoing notices it is of course open to any 

 naturalist to doubt if they can, one and aU, be said to refer to ^the 

 same species of parasite ; yet, notwithstanding divergencies of 

 statements, if any one will take the trouble to examine all the 



