124 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.84 



First segment shorter in proportion to its width than in the other 

 species; median crests extending less than halfway to the front 

 margin, the four inner crests closer together than the others; inner 

 pair of crests parallel; surface smoother in front of the crests than 

 between them. 



Transition to the fidl number of dorsal crests occurs on segment 16. 



Primary crests prominent and with a few scattered pits on the 

 sides below the apex in an irregular row; apex somewhat thickened 

 and of uniform height. Secondary crests conspicuous; on some of 

 the anterior segments the median pair and occasionally some of the 

 other crests extend to the liind margin ; on the middle and posterior 

 segments the median pair of crests extend farther caudad than any 

 of the others, sometimes reaching the hind margin, the other crests 

 crossing three-fifths or four-fifths of the segment; behind the second- 

 ary crests the surface of the dorsum is not lowered as in some of the 

 other species, especially pr^otenta. Surface between both classes of 

 crests scaberulous, with indications of scattered pits. 



Lateral carinae less prominent than in the other species ; rectangu- 

 lar in outline, the front angle broadly rounded, the hind angle nearly 

 square, sometimes a little produced backward; lateral margin con- 

 tinuous, scarcely rounded, paralleling the side of the body (fig. 

 16, d). Poriferous impression longer than in the other species, oc- 

 cupying the margin except for a short distance in front of the hind 

 angle on all but a few anterior segments, on the foremost of which 

 only the anterior half of the margin is occupied; rim around the 

 impression of uniform height, not thickened, and with a few incon- 

 spicuous pits in an indefinite row on the side. Below the lateral 

 carinae are two primary crests scarcely more prominent than the 

 dorsal crests and no thicker. 



Anterior subsegments with the posterior channels longer than 

 broad, the intervening lines moderately high and distinctly beaded; 

 reticulations in front of the channels distinct, the lines through 

 them fine but somewhat more prominent than in saxetana. 



Last segment with 10 setae on the dorsal surface. 



Anal valves with the margins slightly raised and thickened, the 

 disk of each valve not locally inflated but slightly and evenly convex 

 throughout. 



Male gonopods (fig. 16, <?) with the expanded apical portion of 

 each erect piece small, the tip directed forward; branched arm 

 short and stout, arising from near the base and inside the slightly 

 rolled expansion; arm with three apical prongs, the uppermost of 

 which is long, pointed, and erect; the middle prong shorter, directed 

 forward and divided at tip into 6 or 7 very small, rather short, 



