president's addeess. 69 



steadily gaming ground tliat metamerism is everywhere and in all 

 its forms secondary, and therefore valueless as a criterion of class 

 relationship. Equally interesting, is Pruvot's discovery ' that Myzo- 

 menia [Dondersia) hanyulensis is in the young condition the bearer 

 of dorsal plates — important this, as affecting the rescue of the 

 ]S'eomenida3 from a dangerous association with the Platodes, and 

 full of meaning in its general bearings upon simplification of 

 organization. 



We turn now to the Cephalopoda. One direct result of the recent 

 salting of the European market with Pearly JN^autili has been a very 

 useful paper by Mr. Graham Kerr, of Christ's College, Cambridge, 

 dealing^ with some disputed points in the anatomy of that animal. 

 Passing over his work upon the body-cavity, which has altogether 

 special bearings, and his discovery that the lamellar organ is functional 

 as a receptaculum seminis, it is interesting to find in this archaic 

 Mollusc a plate-like ovary, akin in its fundamental characters to 

 that occurring at the base of the vertebrate series. Thanks to 

 Mr. Kerr's work, we are justified in concluding that the assumption 

 of a " cystoarian " condition by the higher vertebrate and molluscan 

 types is unquestionably expressive of a parallelism of modification 

 of corresponding parts. 



Interest in Mr. Kerr's inquiry is greatest as involving a re- 

 determination of the morphology of the "arms" of Cephalopoda. It 

 is needless to recapitulate details concerning the rival theories of 

 Leuckart and Huxley that they are pedal, and of Grobben and otliers 

 that they are circumoral in origin ; suffice it to say that Kerr, taking 

 his stand upon the homologizing of the Cephalopod " funnel" with the 

 whole " foot " of the Gastropoda, and upon the conviction that there 

 is insufficient justification for the assumption that any one ganglionic 

 mass of the Cephalopod can be really said to correspond to the "pedal" 

 ganglion of tlie Gastropoda, makes out a plausible case for the 

 upholders of the pedal theory. He appears to me, however, to have 

 been working under too great a bias in favour of the ai'gument for 

 a Platode ancestry of the Mollusca. His substantiation of the pedal 

 nature of the "funnel" is certainly borne out by the condition in 

 Nautilus, and it receives considerable support from Jatta's recent con- 

 clusion''' that the funnel (Miiller's or Verrill's) organ of the Cephalopoda 

 is a mucus-secreting structure, homologous with the pedal gland of the 

 Gastropoda. His observations do not appear to me to render it still 

 impossible, however, that the "funnel" may not be mesopodial, and 

 that therefore the cephalic tentacles may be propodial and, after all, 

 pedal. The last word has not been said upon this important question. 



As Mr. Kerr's paper was passing through the press, there appeared 

 a valuable monograph by Haller,^ based upon material collected by 



^ Comptes Rend. Acad. Sci. Paris, torn, cxi, p. 689. 

 2 Proc. Zool. Soc. 1895, p. 664. 

 ^ Jatta, Boll. Soc. Nat. Napoli, ser. I, torn, vii, p 45. 



* Ilalk.r, Semon's " Forschiingsreiseu in Austi-. und i. d. Malayischen Arcbipel." 

 See Deulischr. Med. Natiu'w. Gesellsch. Jena, Bd. viii, p. 187, 1895. 



