REPORT ON A COLLECTION OF AMPHIOXOS. 369 



of median and paired fins. As to their phylogeny, he said, 

 " As the dorsal and anal fins were specialisations of the median 

 folds of Amphioxus, so the paired fins were specialisations of 

 the two lateral folds which are supplementary to the median 

 in completing the circuit of the body. These lateral folds, 

 then, are the homologues of the Wolffian ridges in embryos of 

 higher forms." 



Shortly afterwards Mivart also came independently to the 

 conclusion that the paired and azygos appendages of Verte- 

 brates were fundamentally of the same nature. Subsequent 

 palaeontological researches have only confirmed this view. 



The point, however, which is at issue on the present occa- 

 sion is whether or not the primitive continuous lateral fins are 

 represented by the metapleural folds of Amphioxus. From 

 what has been said above there seems to be good reason to 

 expect that this question will sooner or later be answered by 

 the consensus of morphologists in the affirmative. 



Reference should be made here to an interesting feature in 

 the geographical distribution of Branchiostoma, which does 

 not appear to have received sufficient attention. 



The areas of distribution of the species of Branchiostoma 

 are, as a rule, separated from one another by such wide inter- 

 vals of space that it is extremely surprising to find an instance 

 of the overlapping of two specific areas. Such an in- 

 stance apparently occurs in the Torres Straits. 



According to Dr. Giinther specimens of Branchiostoma 

 Belcheri were obtained by Dr. Coppinger from the sea around 

 Prince of Wales Island, Torres Straits, while during the same 

 voyage (H.M.S. *^ Alert") B. cultellum was obtained from 

 the neighbouring Thursday Island. B. Belcheri, Gray, which 

 is characterised chiefly by the presence of sixty-four or sixty-five 

 myotomes, and is more elongated than B. lanceolatum, was 

 first obtained by Sir E. Belcher, during the cruise of H.M.S. 

 "Samarang," from the coast of Borneo. 



Professor Haddon does not appear to have obtained any 

 specimens of Amphioxus from Prince of Wales Island; but the 

 fact that his large collection, taken from several different 



