DESCRIPTIONS OF NEW SPECIES OF PARASITIC COPE- 

 PODS IN THE COLLECTIONS OF THE UNITED STATES 

 NATIONAL MUSEUM. 



By Charles Branch Wilson, 



Of the Department of Biology, State Normal School, Westfield, Mass. 



INTRODUCTORY. 



The species described in the foilowing paper were obtained from 

 different sources, the first two from the American Museum of Natural 

 History of New York City, and the hist three from the United States 

 National Museum. The two former were sent to the author for 

 identification. After it had been determined that they represented 

 new species of Argulus and Aclitheinus, respectively, the American 

 Museum very courteously allowed duphcates to be selected from them 

 and deposited in the National Museum to serve as cotypes of the 

 species. The other three species were all taken from the gills of a 

 single fish, a Polynemus tetradactylus , from Batavia, Java, from the 

 collection of the United States National Museum. These three 

 belong to the genera Caligus, Parapetalus, and Lemanthropns, 

 respectively. The first of these had been very imperfectly described 

 and figured by Bassett-Smith, the second was wrongly referred by 

 the same author to the genus Caligus, while the third is new to science. 

 A brief record is here introduced of the finding, on the California 

 coast, of another species, Achtheinus dentatus, wliicli had previously 

 been recorded only from South America. 



In aU, therefore, the present paper deals with six species, of which 

 three are new. 



DESCRIPTIONS OF NEW SPECIES. 



ARGULUS INGENS, new species. 



Plates 30 and 31, fig. 7. 



Female. — Carapace elliptical, one-sixth longer than wide; antero- 

 lateral sinuses sharply defined but not very deep; posterior sinus 

 narrow, two-fifths the length of the carapace, with parallel sides; 

 lobes not quite reaching the abdomen and narrowed posteriorly, but 

 covering all of the swimming legs except the very tips. 



Proceedings U. S. National Museum, Vol. 42— No. 1900. 



233 



