96 



p. 7, 1855) discovered a peculiar tubular structure in fossil fish- 

 scales, which he regarded as being occasioned by parasites, and 

 possibly by Infusoria, but he was not able to give any good proof 

 of this hypothesis. The same must be said of E. Claparede (Mull. 

 Archiv, 1857, p. 119), who found similar canals in the test of 

 Neritina fluviatilis, and showed that they do not really belong to 

 the shell, without being happier in determining the nature of the 

 parasite, only suggesting that it might possibly be a sponge. 



Such was the state of things, when Prof. Wedl of Vienna and I, 

 independently of each other, took up the question. The observations 

 of Wedl, which concern only the parasites of the shells of Bivalves 

 and Gasteropods, were communicated to the Vienna Academy on the 

 14th of October, 1858, and are therefore previous to my own, which 

 were presented to our Wiirzburg Society on the 14th of May, 1859 ; 

 but I received Wedl's memoir only on the 16th of May, and may 

 therefore say that my observations, which are also extended over many 

 more groups of animals, were quite independent of those of the 

 Austrian microscopist. This being the case, it may be regarded as a 

 good proof of the correctness of our observations and the truth of 

 our conclusions, that we agree in the principal facts, there being 

 only this discrepancy between us, that Wedl calls the parasites Con- 

 fervce, whilst I regard them as Unicellular Fungi. The botanists 

 will decide this question better than we ; only I beg leave to say, that 

 all the numerous parasites observed by myself were unicellular, and 

 that the sporangia were quite of the same kind as those of uni- 

 cellular fungi. I may further add, that the frequent anastomoses 

 of the parasitic tubes remind one of the anastomoses observed in the 

 mycelium of some unicellular fungi, whereas such connexions have 

 not yet, so far as I know, been observed amongst the Conferva. 



I now give a short enumeration of the animals in whose skeleton 

 I observed these vegetable parasites. 



1. Spongice. 



Two undetermined species of sponges, which I got through the 

 kindness of Mr. Bowerbank, show a great many parasitical tubes in 

 the horny fibres of their skeleton. These are most elegant and 

 numerous in one species from Australia, in wh'ich the tubes form a 

 superficial network in the outermost parts of the horny sponge-fibres 

 and more straight canals in their interior, and possess a great many 



