58 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



" Those of specimens 76 and 79, from Detroit Eiver, contained numer- 

 ous specimens of two species of Biatomacecc, viz, Fragilaria ca/pucina^ 

 and StepluDiodiscus niagarce. The former is a filamentous form which 

 grows very abundantly in our lake-inlets attached to stems of lilies. 

 The latter is a large form which, from its peculiar build, contains con- 

 siderable nutritious material. 

 " Very sincerely, yours, 



"S. A. BEIGGS." 



(22 h.) Rate of (jrowth of ichite-fish. — Farther research for the young- 

 fish was unavoidably delayed until the 1st of July. Towards the end 

 of June, from a seine-haul at Waukegan, a specimen of Coregonus albns 

 measuring eight and three-tenths inches in length, one of C. qnadrilat- 

 eralis, measuring seven and four-tenths, and one of Coyegoiiiis harengus, 

 measuring three and four-tenths inches, were obtained. 



At Sault Ste. Marie, Mich., on July 2, with an Indian in a birch 

 canoe, the vichiity both above and below the rapids was explored 

 in the current and in the still water and along the shores, to find the 

 smallest grade of while-fishes that were to be had. Along the shore, in 

 the sharp current, schools were found of which the smallest taken meas- 

 ured four inches and nine-tenths, and the largest six inches and one- 

 tenth. It was quite evident that they had all been hatched the same 

 season. Another excursion in the birch resulted in nothing materially 

 different. The minimum measurement of the next grade taken was 

 eight inches and three-tenths. 



At Shoal Island, one of the Apostle Islands of Lake Superior, a white- 

 fish was taken from the pound-net about the middle of August, measur- 

 ing six inches in length, and another measuring six and one-half inches. 



On the 3d of December, at Point Edward, Canada, at the outlet of 

 Lake Huron, two specimens of Coregonus albus were obtained from a seine, 

 one measuring six inches and eight-tenths, and the other seven inches 

 and seven-tenths. 



It is very probable that the Shoal Island fishes of August and the 

 Point Edward ones of December 3 were the larger-grown individuals 

 of the same generation as those taken at Sault Ste. Marie in July. The 

 difficult point to decide was in what year the beginning of this genera- 

 tion should be placed. 



The only positive data with reference to the growth of white-fish, are 

 found in the observations of Mr. Samuel Wilmot, of Newcastle, Ontario, 

 in charge of the government hatching-house of Canada. 



Mr. Wilmot reports that- in ]N"ovember, 1868, he placed a quantity of 

 Spawn in the hatching-troughs for an experiment, and in the following 

 March and April a large number of young fry made their appearance. 

 He failed in finding food adapted to the young fish, but a number that 

 escaped through the screens were carried down to a small pond where 

 they seemed to thrive and soon became well-developed young fish. In 



