FAMILY ACIPENSERIDAE 79 



the entire summer and early fall at Lake of the Woods making a careful 

 study of the problem, in both American and Canadian waters. Failing 

 to procure any ripe fishes that season. Surber took a number of adults 

 5 to 6 feet long and wintered them at Le Claire Point in a specially con- 

 structed enclosure at the Curry Fishery and so continued observations 

 on these penned fish during March, April, and May 1912. 



Supplemental observations were made on additional fish procured 

 at the mouth of Rainy River in April and May. The net result of these 

 observations was the finding that the rock sturgeon spawned over a 

 period of several months, depositing a few eggs at a time wherever it 

 might be at the moment. This conclusion was based on the condition of 

 the ovaries of upward of 40 adults which were examined critically. Eggs 

 in all stages of development, from those scarcely one-fiftieth of an inch 

 in diameter through all stages to those one-fifth of an inch in diameter 

 and nearly ready for extrusion were found in the same fish. 



In the early 1890's the Michigan Conservation Department succeeded 

 in procuring ripe fishes from which they hatched several hundred thou- 

 sand fry for two seasons. About 1903 the United States Bureau of 

 Fisheries again procured some eggs and hatched them successfully at 

 the Swanton, Vermont, Station (Carter. 1904) . In the discussion follow- 

 ing this report some interesting facts developed on the methods of 

 handling eggs, the difficulty of procuring ripe fish, the size of the eggs, 

 and the percentage of hatch. 



GENUS Scaphirhynchiis Heckel 



This genus includes only one species, the characters of which are 

 given below. 



HACKLEBACK (Shovelnose Sturgeon, Switchtail) 

 Scaphirhynchus platorynchus (Rafinesque) 



The hackleback or shovelnose sturgeon (Figure 4B) can be readily 

 distinguished from the lake sturgeon by its longer snout and by the 

 absence of a spiracle. It rarely exceeds a length of 3 feet or a weight of 

 5 or 6 pounds. The average is about 28 inches in length and approxi- 

 mately 3 pounds in weight. The body of this species is more slender 

 than that of the lake sturgeon, the long slender tail extending fully twice 

 as long as that of the lake sturgeon. The large caudal fin terminates in 

 a long filament nearly if not quite equaling the rest of the fin. It also 

 differs from young rock sturgeon of corresponding size in that small 

 bony shields completely cover the tail, which is flattened from above. 

 The snout is broad, flat, and shovel-shaped. Unlike that of the immature 

 and adult rock sturgeon, its color is a uniform pale yellowish olive, 

 without spots or blotches. 



The hackleback ranges from the Hudson Bay drainage of the Cana- 



