8 ANATOMY OF AMPHIOXUS. 



that he had absolutely discovered it, but subsequently came 

 across Pallas's description. He showed that it was ajis/i 

 allied to the Cyclostomata, a group which includes the 

 lampreys and hag-fishes. 



In his account of its habits he pointed out how sensitive 

 it was to light, and although without apparent eyes, yet the 

 light stimulated it to such an extent that it could by no 

 means tolerate it. Costa mistook the curious tentacle-like 

 processes or cirri, which form a circlet round the mouth 

 (see Fig. i, p. 12), for respiratory filaments or branchiae, 

 which suggested to him the name of Branchiostoma for the 

 genus, the specific name given by him being Inbricnm, 

 referring to the way in which it slips through the fingers 

 with the rapidity of an electric spark when touched. 



WILLIAM YARRELL, in his History of British Fishes 

 (1836), was the next to describe the remarkable creature 

 and to give it the name Amphioxus, by which it has become 

 so well known and which refers to the fact that it is pointed 

 at both ends. Yarrell was also the first to describe the 

 notocJiord or chorda dorsalis of Amphioxus as a cartilagi- 

 nous vertebral column. 



Subsequently other observers had taken specimens of 

 Amphioxus from various points, notably from the coast of 

 Sweden, so that the attention of morphologists was at 

 last definitely directed to the interesting form, and in 

 1841 there were produced three independent memoirs on 

 the anatomy of Amphioxus, which laid the foundation 

 of our present knowledge. The authors of these memoirs 

 were JOHN GOODSIR of Edinburgh, HEINRICH RATHKE of 

 Konigsberg, and JOHANNES MULLER of Berlin. The work 

 of the last-named author is a masterpiece. With regard 

 to the systematic position of Amphioxus, the outcome of 

 all these researches was, that it was allied to the Cyclo- 



