N... 1302. A MERIGAN PARASITIC A RG ULID.E— WILSON. 719 



face of the carapace thickly covered, over its anterior' half, with large, 

 sharp spines. 



These spines are found on every species in greater or less abundance, 

 but they are especially large and prominent on aiuericanus. The color 

 is a pale brownish white, sparsely covered on the ventral and dorsal 

 surfaces with small pigment sjwts of a slightly darker hue. When 

 alive this species is particular!}^ transparent, and shows the side rami- 

 ticatioiis of the stomach very plainly. (See photograph, tig. 8-i.) This 

 is one of our most typical American fresh-water species. The Ameri- 

 can continent, with the accession of the species here added, resumes 

 once more the old position accorded it by Kroyer and Thorell as the 

 proper habitat of the genus Argulus; and, lastly, the only host upon 

 which this particidar species has thus far been found is a genus of tish 

 exclusively American (Amia). These reasons have suggested the spe- 

 cific name americanus as appropriate. 



Length 10 mm. ; length of carapace 8 nun. ; breadth of carapace 8 

 mm.; length of abdomen 2.5 mm.; breadth 4 mm. 



This species infests Amia calva Linnaeus in our Great Lakes region 

 to such an extent as to become a nuisance when the fish are kept in 

 aquaria. About 100 specimens were sent to the author by Prof. Jacob 

 Reighard from Ann Arbor, Michigan, who wrote that he had been 

 obliged to have the Amia cleaned to rid them of these pests. He also 

 kindly sent the excellent photograi)hs of the animal as an opaque object 

 which show very clearly its specific characteristics. A dozen of these 

 animals were sent in a mailing case from Ann Arbor to Westfield, 

 Massachusetts, and every one was alive when received and lived for 

 about a week afterwards. 



An efi'ort will be made in the near future to obtain ripe females in 

 this way and follow the development of the sj^ecies. 



This concludes the North American species so far found, just half 

 the entire genus, while of the other half four out of the thirteen spe- 

 cies belong in Central or South America, leaving but nine species 

 from all other localities combined. 



It is well to recall again in this connection that the present is the 

 first attempt to collect all the American species and must therefore be 

 incomplete. By the time anything like as much work has been done 

 in America as in Europe we ma}^ confidently expect that the prepon- 

 derance of American species will be even greater than now. 



Of the thirteen North American species here presented the location 

 of the type of jnujettensls is unknown, if indeed it has not been lost; 

 the types of lej)idostei and stizostethli are in the museum of the Ohio 

 State University, while the types of the other ten species are in the 

 National Museum. Five species are described for the first time; two 

 others are removed from the doubtful list and the missing sex supplied, 

 while the males of five out of the remaining six species are here first 



