20 



mons to be sterile, and also those between the trouts and 

 charrs. If this is so, and I hope it is, then the violation of 

 Nature's laws by man in his efforts to perpetuate monstrosi- 

 ties will be a failure. If man could cross the elephant with 

 the butterfly there would be no limit to his ambition to pro- 

 duce curiosities for dime museums. 



Dr. Kingsbury asked if the food of fish did not color the 

 flesh, and if it was not possible that the rich, red-fieshed trout 

 had not fed upon food of that color. 



Dr. Bean replied that once he had believed that the red 

 flesh of salmon came from crustacean food, but the mackerel 

 and other white-fleshed frsh feed on the same food, and at 

 present he thinks that the color of the food does not affect 

 the color of the flesh of the fish which eats it. 



Prof. John A. Rvder, of the University of Pennsylvania, 

 Philadelphia, spoke on the embryology and histology of the 

 shad. 



THE LATERAL LINE ORGANS AND THE PIYA- 



LINE TISSUES OF THE HEAD 



OF THE SHAD. 



BV PROF. JOHN A. RYDER. 



The common shad of our markets is in many respects one 

 of the most strikingly characteristic fishes amongst the 

 variety of native species exposed for sale in the spring months. 

 The lateral line system of these fishes is interesting from a 

 number of points of view. First, from the consideration of 

 its possible relation to the annual migration of that species 

 into fresh water for the purpose of spawning, and secondly, 

 on account of the very singular histological structure of the 

 skin over a considerable portion of the extent of the system 

 and over the head. 



Whether or not this part of the nervous system of the shad 

 enables that fish to appreciate very slight differences of tem- 

 perature at two points in the water separated only by the 



