REPORT ON A COLLECTION OF AMPHIOXUS. 365 



One of the most remarkable features in the internal organisa- 

 tion of B. cultellum is the fact that the gonads occur as a 

 unilateral series of pouches confined to the right 

 side of the body. 



Singular to say, it agrees in this respect also with the 

 Bahama species, and it should be clearly pointed out that the 

 first discovery of this curious form of asymmetry in Amphioxus 

 is due to Professor Andrews. The fact of its occurrence also 

 in B. cultellum, which is a distinct species with a very 

 different geographical distribution, is of some interest. 



In view of what we know as to the asymmetry of the larva 

 of Amphioxus, I cannot, however, agree with Andrews in re- 

 garding the above species as being generically distinct from 

 the European species, although it might perhaps be legitimate 

 from a systematic point of view to create a new sub-genus for it. 



I have paid particular attention to this asymmetry of the 

 gonads in B. cultellum, and find that it occurs invariably. A 

 great number of specimens in the collection were mature, and 

 they were all examined with great care. In some cases so 

 large were the gonads, extending from one side to the other 

 across the middle line, that a casual glance would lead to the 

 impression that they were paired in the usual way, but a dis- 

 section or a careful examination with a lens always revealed 

 their unilateral disposition. 



All observations were controlled by transverse sections, and 

 in those which passed through the greatly distended gonads 

 the pharynx was found to be pressed tightly against the left 

 wall of the atrium, almost the entire available space being 

 usurped by the gonads. 



In view of the fact of the unilateral disposition of the gonads, 

 both in B. cultellum and in the species from the Bahamas, 

 it is important to note that often in specimens of Amphioxus 

 from the Mediterranean the gonadic pouches of the right side 

 ean be observed to preponderate greatly over those of the left 

 side, as if the hypertrophy of the former led to the reduction 

 or incipient atrophy of the latter. I am not aware that this 

 observation has ever before been recorded. 



