122 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



to acknowledge them as "Worms, and took the same view as Verany 

 and Krohn. 



Lacaze-Duthiers, however, in 1874 (Arch. Zool. Exp. et Gen., 

 iii, p. 30), took the opposite attitude, and described a Tethys covered 

 with parasites which, he said, had long been known under the name 

 Fcenicurus. This opinion was not shared by Eergh, who in his 

 monograph on Tethys, in 1875 (Malak. TJnters. (C. Semper, Reisen 

 im Archipel der Philippinen, ii, ii, Wiesbaden), Heft ix, pp. 345 et 

 seq.), showed that the bodies definitely belonged to the Mollusc, and 

 that they were homologous with the dorsal processes of Eolis, a view 

 also held by von Ihering in the year following (Morph. Jahrb., ii, 

 1876, pp. 27 et seq.). 



Lacaze-Duthiers, writing again in 1885 (Comptes Rendus, ci, 

 pp. 30-5), still regarded the bodies as parasites on Tethys. In this 

 paper he described how they contracted and changed in form 

 repeatedly after being separated from the body of the host. He 

 noted that they were acoelomate animals, with a much branched 

 digestive system, with no anus, with a definite muscular system, and 

 with a nervous system consisting of two ganglia and two principal 

 nerves arising from them, and a nerve commissure between the 

 ganglia. The conclusion he came to, as the result of his investi- 

 gation, was that the animals were Dendrocoel Planarians, degraded 

 by a parasitic mode of life. He failed to find any reproductive organs, 

 but this he attributed to the fact that he collected his specimens in 

 May, when presumably they were not ripe for breeding. 



By way of rejoinder, Bergh asserted in the following year (Arch. 

 Zool, Experim. (2), iv, 1886, pp. 73-6) that the dorsal appendages 

 of such Kudibranchs as Tethys fall off readily, and retain their 

 vitality for several hours after separation, that the alimentary canal 

 of the ' Phoenicure ' is a branched prolongation of the hepatic caecum 

 of the Tethys, and that the papilla to which the mouth of the 

 ' parasite ' is attached is the torn stalk of the hepatic caecum. 

 Lacaze-Duthiers, far from being convinced, followed with a complete 

 description of the anatomy of Phoeiiicurus varius, illustrated by two 

 coloured plates (ibid., pp. 77-108). He adhered to his former view 

 that the body in question was a Dendrocoel Worm parasitic on the 

 Mollusc, and concluded by remarking that he would not believe that 

 the Phoenicure was an appendage of the Tethys until specimens of 

 that Mollusc had been bred in captivity and found to develop such 

 bodies. 



In the course of the discussion which followed the President called 

 attention to the suggestion made by Professor Herdman and Mr. Clubb 

 that the chief function of the cerata or dorsal papillae of Nudibranch 

 Mollusca is in some cases to protect the animal by contributing to 

 their inconspicuous appearance, and in other cases to render the 

 animal conspicuous, and to warn predaceous animals of some offensive 

 property (Trans. Liverpool Biol. Soc, iv, 1890, p. 131 ; also 

 W. A. Herdman, Quart. Journ. Micro. Sci., xxxi, 1890, p. 55). 



Mr. R. H. Burne exhibited two partially dissected specimens of 

 Spirula. The most perfect of these comprised the whole animal with 



