126 American Fisheries Society 



favor one side over the other. Not until the young fish is 

 fully three-eighths of an inch in length can the first 

 slight difference be perceived in the position of the two 

 eyes (when seen from above), the left eye being some- 

 what in advance of the other." In all the fishes that I 

 have examined the metamorphosis is practically com- 

 pleted before the fish has reached this size. The meas- 

 urements given by Wiliams correspond to my own, and 1 

 think they may be taken as typical for this species. 



Williams found a fish that metamorphosed at 14 mm. 

 and tentatively called it Limnnda ferruginea Storer. This 

 may have been the species that Agassiz was studying. I 

 have not examined the young of this species and Williams 

 was not sure of his identification, and this is simply given 

 as a suggestion as to the species Agassiz was working 

 with. 



When we turn to the plates we find that there is not 

 only a difference in the size of the species but also that 

 the time relations between the eye migration and the de- 

 velopment of the tail are different from the conditions in 

 P. americanus. In the species figured here the tail de- 

 velopment is relatively much more rapid. It is probable 

 that the development of the tail as described by Agassiz 

 (1) is for another fish. It would seem that the same er- 

 ror would be made in both cases. The value of the work 

 as far as it relates to the development of the tail is not 

 impaired but it is probably the tail of a fish other than P. 

 americanus. 



Material and Apparatus. The sources of my material 

 were the Rhode Island Hatchery at Wickford and the 

 United States Hatchery at Woods Hole. The material 

 collected at Wickford is referred to as Lot 1 and Lot 2. 

 Lot 1 consists of fry that were hatched from eggs stripped 

 from the female and fertilized March 26. In this lot there 

 was also a small number hatched from eggs fertilized 

 April 7. The difference in the time of fertilization will 

 account for the differences in the rate of growth for this 

 lot. The fishes in lot 2 are from females that were al- 

 lowed to spawn and the eggs fertilized by males kept in 



