50 Bulletin, Vanderbilt Mar'ine Museum, Vol. II 



little shorter than the second and has its lateral margins less flaring ; 

 the fourth and fifth segments are successively shorter and decidedly 

 vaulted ; the sixth segment is very small ; the telson is a small, trian- 

 gular protuberance, narrowing posteriorly and with the apex rounded. 

 There are four pairs of abdominal appendages in the female which 

 arise from the second to fifth segments respectively. Each branch is 

 slender and narrow, arching inward toward the median ventral line, 

 and is heavily fringed with long, multiplumose setae. The female 

 apertures are on the ventral face of the coxal joints of the fourth pair 

 of legs. The male appendages consist of a pair of long articles which 

 seem to arise from the under side of the third abdominal segment 

 where a bifurcation of the trigonal under part of the abdomen occurs ; 

 the basal part of the first pair of appendages is flattish and bent, 

 forming a short, peduncular article; the distal article is enlarged 

 proximally, where it is irregularly shaped, convex, and has an internal 

 cavity in which the distal part of the second pair of appendages is 

 encased ; the first pair of appendages narrows distally into a somewhat 

 compressed, cylindrical rod which has the extreme tip flattened and 

 produced into a membranaceous semicircular process with the ends 

 or tips pointing posteriorly. The second pair of appendages appears 

 to arise from the fourth abdominal segment, close behind the first pair 

 of appendages which it resembles ; the peduncular being quite similar 

 but smaller, the distal article being dilated differently, forming a 

 rounded, compressed node, beyond which the distal three-fourths of the 

 article tapers abruptly to an acuminate tip which is sheathed in the 

 central cavity of the dilated portion of the first pair of appendages. 

 The lateral margins of all the abdominal segments are heavily set with 

 long plumose setae, as are also the under surfaces of the proximal 

 joints of the fourth pair of legs. This pilosity surrounds and con- 

 ceals the male appendages. 



The inner antennae have the first visible peduncular article rather 

 wide and long, reaching as far forward as the distal margin of the 

 second joint of the outer antennae ; and armed at its inner distal angle 

 with a series of exceedingly long, plumose setae which extend as far 

 forward as the distal end of the third article ; the second article is only 

 about half as long as the preceding one and is small, cylindrical; the 

 third article is similar to but nearly twice as long as the second, the 

 fourth article is similar to the third but not quite so long, and the 

 supports the biramose flagellum, which has an outer branch composed 



