40 ANATOMY OF AMPHIOXUS. 



3. (p. 10.) On those occasions on which Amphioxus is not 

 buried in the sand, but lies on the surface of the sand, occasions 

 which frequently occur when it is kept in captivity, and especially 

 after having been confined for a considerable length of time, it 

 lies on one side, as mentioned in the text. The percentage of 

 instances in which it lies on the right or left side has not been 

 taken, and consequently it is not possible to say that it prefers lying 

 on one side rather than on the other. Since the olfactory pit and 

 the anus occur on the left side, it is conceivable that it prefers 

 to lie on the right side. If this had been a definite habit, it 

 would probably not have escaped the observation of Johannes 

 Miiller. It is a fact which is too frequently overlooked, that the 

 lying on one side is entirely incidental, and is emphatically not 

 the result of adaptation to a peculiar mode of life, as it is in the 

 case of the Pleuronectidae. 



4. (p. 1 1 .) Species and Distribution of Amphioxus. A useful 

 synopsis of the genus Branchiostoma has recently been prepared by 

 ANDREWS, as an appendix to his paper on the remarkable species 

 which occurs at the Bahamas. In this species there is a long 

 caudal process into which the notochord extends. It is an active 

 swimmer. Gonadic pouches are only present on the right side, 

 those on the left being suppressed. The latter is also true of 

 Branchiostoma cultclhim. The peculiarities of the species from 

 the Bahamas were such that Andrews deemed it necessary to form 

 a new genus, Asymmetron. 



In the table of species on page 41 it will be noticed that the 

 lengths of the different species are not in any proportion to the 

 number of myotomes. 



Insufficiently described species occur off the coasts of Japan, 

 Ceylon, and Fiji Islands. It is interesting to note that while in 

 Europe, Amphioxus occurs as far north as Scandinavia, on the 

 Atlantic coast of North America, Chesapeake Bay appears to be 

 its northern limit, and it is therefore wholly unknown at the 

 Marine Biological Station at Woods Holl. Attention may further 

 be called to the simultaneous occurrence of two distinct species, 

 B. ciiltelhim and B. belcheri, in the Torres Straits. B. cultellum 

 is easily recognisable on account of the unusual height of its dorsal 

 fin. 



