154 American Fisheries Society 



of control. In the summer of 1914, Dr. A. D. Howard,* of the 

 Fairport Station, reared about 200 young mussels of the species 

 Lampsilis luteola from an artificial plant in a floating crate in the 

 Mississippi River. The same summer Mr. A. F. Shira, then at 

 the Homer, Minnesota, Station, reared six young mussels of the 

 same species in a small balanced aquarium. It may also be noted 

 here that the same summer several hundred young mussels of 

 the same species were first reared in one of the ponds of the 

 Station. 



The experiments were conducted in a series of eight galvanized 

 iron troughs, placed at a sufficient low level to receive a gravity 

 supply of water from Pond ID. This pond was supplied by 

 gravity from the reservoir which in turn received its supply direct 

 from the Mississippi River through the pumping plant. The water 

 in pond ID remained comparatively clear throughout the season and 

 this was one of the primary considerations in locating the troughs. 

 The troughs were twelve feet long, one foot wide and eight inches 

 deep, painted with asphaltum, and each had its independent 

 inflow from a common, screened supply pipe in the pond. The 

 bottom of each trough was covered with fine sand to a depth of 

 about one-half inch. 



Records were kept of the progress of the larval mussels through 

 the process of development and when they had reached that stage 

 when they were ready to drop from the fish, counts on the fish 

 gave a close approximation of the number dropped in the trough. 



The results of the experiments the first season were quite 

 meager, as only seven young of L. luteola, varying from 6 mm. to 

 17.8 mm. in length, and four L. ligamentina with an average 

 length of 2.6 mm. were reared. However, in case of the ligamentina 

 the results were very encouraging, as it marked the first instance 

 of juveniles of this species being artificially reared to this size. 



During the season of 1918, greater results were obtained with 

 luteola; the young mussels being successfully reared in four 

 troughs. In one trough a count of 746 was obtained. The 

 experiments with ligamentina gave negative results, though a lack 

 of glochidia for infection greatly handicapped the work with this 

 species. 



* "A New Record in Rearing Fresh-Water Pearl Mussels." A. D. 

 Howard, Trans. Amer. Fisheries Society, Vol. XLIV, No. 1, 1914. 



