Description of the Argulus Catostomi. 297 



Art. XVIII. — Description of the Argulus Catostomi, a new pa- 

 rasitic Crustaceous animal, (with figures.) By J. D. Dana and 

 E. C. Herrick, Members of the Yale Nat. Hist. Soc. 



Read before the Yale Nat. Hist. Soc. June 2, and Aug. 4, 1836. 



For our knowledge of the existence of the interesting animal 

 which we have attempted to describe in the following paper, we 

 are indebted to Mr. Philos Blake of this city. Early in the 

 spring of 1835, this gentleman, whom we have always found ready 

 to do a service to the cause of science, very kindly brought a spe- 

 cimen for our examination. This was accidentally destroyed before 

 it had been fully investigated, and nothing further was done concern- 

 ing the matter for that year. During the past season however, 

 through the attention of the Messrs. Blakes, and of several of the 

 intelligent workmen engaged in their establishment, we have been 

 liberally supplied. 



A slight examination sufficed to show that the animal was closely 

 related to that singular crustaceous parasite, which has attracted so 

 much deserved attention, the Argulus foliaceus of Jurine, Jr.* 

 The resemblance is so great that a hasty observer might conclude 

 that the two are specifically identical ; but after considerable study 

 we are convinced that they are not. The correctness of this result, 

 we hope to make apparent in the following pages. 



The animal before us has been found at various times in the wa- 

 ters of Mill river, near Whitneyville, just below the fall at the man- 

 ufactory there established. We have discovered none above the 

 fall, but have been told that for a mile above, they are occasionally 

 seen. It may not be irrelevant to mention that the tide-water of 

 'New Haven harbor flows up as far as the fall, so that the stream 

 here has a large admixture of sea-water. It infests the fish here 

 called the Sucker. The fish evidently pertains to the genus Catos- 

 tomus of Le Sueur, a monograph of which is given by him in the 

 Journal of the Academy of Natural Sciences of Philadelphia, Vol. I, 

 (8vo. 1817.) We cannot satisfactorily determine whether it is his 

 C. Bostoniensis or C communis, and are somewhat inclined to think 

 that on further examination they may prove varieties of one species. 



* The elaborate memoir of this author contained in the Annales du Musdum 

 d'Hist. Nat. de Paris, 4to. tome VII. (1807,) has been our chief source of iufor- 

 mation concerning this species. 



Vol. XXXI.— No. 2. 38 



