370 ARTHUR WILLEY. 



stations in Torres Straits, does not contain any other species 

 than B. cultellum is noteworthy, and it would be a matter 

 of interest to determine the exact relations to one another, 

 and limitations in the distribution of the two species of 

 Branchiostoma which have been recorded from the Torres 

 Straits. 



A great deal of work has still to be done in connection with 

 the geographical distribution of Amphioxus, and this not only 

 with regard to its distribution on the face of the earth, as to 

 which we can hardly hope for a speedy settlement of the ques- 

 tion, but even as to its distribution in more restricted pro- 

 vinces, as, for example, the coast of Europe. Although there 

 is only one species, there are undoubtedly several varieties of 

 European Amphioxus which differ from one another in point 

 of size. Thus the Messina Amphioxi average larger than 

 those from the Gulf of Naples, while both of these varieties 

 would appear to come far short of that found on the coast of 

 Brittany, which is said to attain a length of no less than 

 8 cm. 



An extensive series of measurements of European Amphi- 

 oxus from different localities would be certain to yield 

 important results 



It is worthy of note that differences in size among indi- 

 viduals or species of Amphioxus are not causally related to the 

 number of myotomes. A single instance will suffice to illus- 

 trate this point. The Bahama species, according to Andrews, 

 has sixty-six myotomes, with a length of only 13 to 16 mm. 

 B. lanceolatum has sixty myotomes (sometimes fifty-nine 

 and sometimes sixty-one), with a length of 4 to 6 and even 

 8 cm. 



The relation of size to physical or organic environment is a 

 subject for investigation. 



In conclusion it may be said that Professor Haddon's collec- 

 tion, which I have had the privilege of examining, has enabled 

 the specific characters of Branchiostoma cultellum to be 

 definitely ascertained, and has brought to light several interest- 

 ing features in its organisation. 



