233 



notochord of Balanoglossus must he looked for near the anus of Ce- 

 phcdodiscus\ and so on! 



Still the Professor leads us on like a conjuror. The Vertebrata 

 themselves are in the same plight as Balanoglossus. We are all Tro- 

 chophores turned round and turned over — 'L'embryon du Verté- 

 bré est un Trochophore renversé'. Can any zoologist venture to 

 contradict such a patent hypothesis? My own impression in reading 

 these conclusions of Professor Roule w^as that they are of more real 

 service to Science than all the pages preceding them. For if this sort 

 of thing Avill not serve to put an end to the copious stream of theories 

 of vertebrate origin, involving morphological somersaults and structural 

 contortions, nothing will. 



The conclusion of the Avhole matter appears to be this: 



1) That Professor Roule denies entirely the method of mesoderm 

 formation in Actinoirocha by localized hypoblastic ingrowths, as de- 

 scribed by me. He does this on the strength of his observations upon 

 another species, without having furnished the slightest direct evi- 

 dence for the origin suggested by himself. 



2) That he sweepingly condemns my assertions regarding the 

 structural features of the late larva found at St. Andrews (and with 

 them, those of nearly every other worker who has preceded him, upon 

 Mediterranean larvae) , because he has failed to find the same features 

 in the species investigated by him. 



3) That, based upon the archaic notion of the homology of the 

 blastopore, he has been led to conclusions regarding the relationship 

 of Cephalodiscus to Balanoglossus, and of Invertebrates to Vertebrates, 

 which border on the ludicrous. 



4) That he has seen fit in his criticism to accuse me of erroneous 

 assertions and exaggerations, and to use other expressions of a very 

 strong nature. 



I only ask: — Are the first three 'Science', and is the last in good 

 taste ? 



Edinburgh, School of Medicine, March 1901. 



3. On the Composition and Variations of the Pelvic Plexus in Acanthias 



vulgaris. 



By R. C. Punnett, B.A. 

 (Royal Soc. London, Abstract.) 



eingeg. 14. März 1901. 



The facts recorded in this paper may be summarised as follows: 

 1) Considerable variation occurs in Acanthias vulgaris with re- 

 gard to: 



