NO. 1900. NEW SPECIES OF PARASITIC COPEPODS— WILSON. 2.35 



fringed with a dense row of long fine liairs; tlie proximal joint of tli<> 

 second legs has a lunate process on the ventral surface near the distal 

 end, the two ends of the process curving over ventrally toward each 

 other; the proximal joint of the tlurd legs has a finger-like process 

 at the distal anterior corner and a dense tuft of fine hairs opposite 

 on the posterior margin; the fourth legs have the usual peg on the 

 anterior distal margin of the basal joint, while the booMike process 

 is fringed with long and very fine hairs (see fig. 4). 



The accessory sexual apparatus is thus more complicated than 

 usual and is peculiar for the abundance of dense hair fringes. 



Color (preserved material, both sexes) a uniform yellowish brown, 

 marked with small spots of darker brown over most of the carapace 

 and the center of the abdomen. 



Total length of female, 21.5 to 25 mm. ; of male, 16 mm. Carapace 

 of female, 14.5 mm. long, 12.5 mm. wide. Abdomen, 7 nam. long, 5.5 

 mm. wide. Carapace of male, 12 mm. long, 9 mm. wide. 



dngens, of very large size.) 



This species can be recognized by its great size, by the approxima- 

 tion of the two outer spines on the basal plate of the maxilliped, and 

 by the complicated accessory sexual apparatus of the male, particu- 

 larly by the dense hair fringes. This is by far the largest American 

 species, and the only foreign species that surpasses it is A. scutiformis 

 Thiele, the female of which is sometimes 30 mm. long. 



Two females and a male of this species were obtained by the Ameri- 

 can Museum of Natural History, tlirough Dr. L. Hussakof, from the 

 mouth of the alligator gar, Lepisosieus tristoschus (Bloch and Schnei- 

 der), in Moon Lake, Mississippi. The male and one female are made 

 the types of the species and are retained by the American Museum. 

 The other female becomes a cotype in the National Museum with Cat. 

 No. 42290, U.S.N.M. 



ACHTHEmUS PINGUIS, new species. 

 Plate 31, figs. 8-14, and plate 32, figs. 15-21. 



Female. — General form more like that of Perissopus than either of 

 the species hitherto described. Carapace trapezoidal, widest across 

 the posterior border, considerably narrowed anteriorly, with nearly 

 straight sides. 



Frontal plates thoroughly fused with the head, their anterior margin 

 entire and evenly rounded, with a shallow sinus at the center. 



Posterior margin of carapace with flattened curves, somewhat 

 reentrant at the center; posterior sinuses shallow and narrow, pos- 

 terior lobes sliort and blunt; lateral areas narrow, with the transverse 

 grooves practically obliterated, appearing only as slight notches on the 

 lateral margins. Dorsal i)lates covering the fused second antl third 

 thorax segments, of the same width as the carapace, elliptical, sepa- 



