roZNTinCATION OF THE GLOCHIDIA OF FRESHWATER 

 MUSSELS. 



By Thaddeus Surber, 

 Assistant, U. S. Biological Laboratory, Fairport, Iowa. 



While carrying on experiments in the artificial infection of fishes 

 with the glochitliinn larvae of freshwater mussels at the Fairport 

 Biological Laboratory, the question of suitable hosts for the various 

 species arose almost at the beginning of the work; for while we were 

 quite successful with certain species others gave but very indifferent 

 results. This naturally led to search for natural hosts of the various 

 species, during which it became necessary to examine the gills and 

 fins of many fishes, a work which, though it has in reality only begun, 

 is already fruitful in results and opens up a wide field for research. 

 In fact, the artificial propagation of the mussel depends to a cer- 

 tain extent upon these results; and my object in writing this paper 

 at the present time is to stimulate such investigation, which will 

 amply reward those who care to take it up. 



The identification of the various species while m a parasitic stage 

 presents some difficulties. The only available figures of glochidia, 

 so far as I know, are those made by Lea,<^ who figures a great many 

 species, but not very accurately as to relative size, etc., and his 

 figures are therefore of little use. Lately Lefevre and Curtis have 

 given some most excellent figures, with measurements, but the 

 species are few. 



The requisite is a complete collection of the various species care- 

 fully mounted, from which proper camera-lucida drawings can be 

 made to a uniform scale. Such a collection has been attempted in 

 the present undertaking, and the figures submitted herewith repre- 

 sent about 40 species, most of them forms occurrmg in the Missis- 

 sippi River in the vicinity of Fairport, but supplemented by a few 

 from the Cumberland Kiver, the Ohio, and a few other points where 

 investigations have been carried on by Mr. H. Walton Clark, the 

 late J. F. Boepi)le, an<l m3"self. 



a Lea, Isaac: Description of the embryonic forms of 38 species of Unionid;c. Journal Acaflemy of Nat- 

 ural Sciences Philadelphia, 2d ser., vol. iv, pi, 5; Description of 52 species of UnionidiH?, ibid., vol. vm, 

 supplement, pi. 21. 



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