412 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxii. 



ease with ever}' zoologist since their day also. Even the present 

 author, in a previous paper on the Aroulifhe, was forced to be content 

 with the one sex in conseqiunice of an unfortunate accident which 

 destroyed the few male specimens he possessed. 



Accordingly this, the best known and one of the most widely dis- 

 tributed American species, has waited almost seventy years for the 

 completion of the original diagnosis. 



In the spring of 190.5 the author visited the State lish hatchery at 

 Swanton, Vermont, on the Missequoi River, near the shores of Lake 

 Champlain. At this station are hatched every year many millions of 

 the eggs of the wall-eyed pike, Stisostedion vitreMm.^ one of the most 

 common food lishes in the lake and its tributaries. The females are 

 obtained for stripping l)}^ means of seines, and through the superin- 

 tendent of the station permission was obtained from the State authori- 

 ties to examine all the tish taken in the seines. For this and for many 

 other courtesies the author acknowledges his indebtedness to the super- 

 intendent, who kindly placed at his disposal every facility which the 

 station afforded. 



Among other iish obtained were several red-lin and black-fin 

 suckers, Catoxtomus nigricans and C. eatostonms^ and from these were 

 taken about twenty specimens, of Argulus eatoHtoiul^ five of which 

 proved to be males. Both sexes of this species were also obtained 

 from the black sucker, C. mtostoruus., caught in Lake Maxinkuckee, 

 Indiana, in August, 1906. 



None of these specimens were as large as those obtained by the 

 author from the same sucker in Massachusetts, l)ut which were acci- 

 dentally destroyed. Swanton, Vermont, is a long way from Mill 

 River in Connecticut, where Dana and Herrick secured their specimens, 

 and Lake Maxinkuckee is even farther removed. 



Furthermore, the water is entirely fresh in both these localities 

 instead of being brackish. But the one lot of material supplements 

 the other and enables us to complete the account begun so long ago. 



ARGULUS CATOSTOMI Dana and Herrick. 

 Plate XXIX, figs 1-9. 



The Male. — Carapace orbicular. al)out one-tenth wider than long, 

 with evenly rounded sides. Posterior sinus very wide, especially at 

 the ))ase, and a little more than one-third the length of the carapace. 

 Grooving of the dorsal surface like that of the female. Abdomen 

 elliptical and relatively nuich larger as would be expected in this sex, 

 about one-third the length and one-fourth the width of the carapace. 

 Testes elliptical, pear-shaped, and fully three-tifths the length of the 

 abdomen, their dorsal surface sprinkled with small dots of dark pig- 

 ment. Anal sinus wide, less than one-third the length of the abdomen; 



