PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 4hd 



Bythocaris uana, sj). nov. 



This is a small species, at once distinguished from B. Payeri and B. 

 gracilis by the very much broader and difiereutly shaped front, and the 

 much longer eye-stalks. 



The carapax is about three-fourths as broad as its length along the 

 dorsum, and the breadth of the front fully a third of the length. The 

 supraorbital teeth are very large, and project as far forward as the \ery 

 small rostral tooth. The median carina of the gastric region is low and 

 inconspicuous. 



The eyes are well developed, placed obliquely upon the stalks, and black. 

 The length of the eye and stalk is about equal to the breadth of the 

 front, and the diameter of the eye considerably greater than that of the 

 stalk, equalling about a fifth the length of the carapax. The first seg- 

 ment of the peduncle of the autenuula reaches a little beyond the eye. 

 and its lateral spine is slender and falls considerably short of the dis- 

 tal end of the segment itself. The outer flagellum is very stout in both 

 sexes, and tapers rapidly to a very slender tip, reaching to, or a little 

 beyond, the tip of the antennal scale. The inner flagellum is very slen- 

 der, and slightly longer than the outer. The antennal scale is shorter 

 than the dorsum of the carapax, a little more than a third as broad as 

 long, and has the tip more elongated than in the last species. The fla 

 gellum of the antenna is very slender, subcylindrical, and much longer 

 than the body of the animal. 



The endopod of the second gnathopod reaches nearly to the tip of the 

 antennal scale; the distal and proximal of the three segments of which 

 it is composed are approximately equal in length; the middle segment 

 is about two-fifths as long as the i>roximal, and the exopod scarcely 

 reaches to the middle of the proximal segment of the endopod and is 

 very slender. The first peraeoi^ods reach to near the tips of the peduncles 

 of the antennae; the carpus and chela are together as long as the rest 

 of the endopod ; the chela is about once and two-thirds as long as the 

 carpus, slightly stouter, about a fourth as broad as long, and the digits 

 slender and a little less than half as long as the whole length of the 

 chela. The second perceopods are very slender and reach considerably 

 beyond the antennal scales; the ischium and merus are subequal in 

 length ; the carpus is a little less than twice as long as the merus, and 

 composed of eight segments ; the chela is nearly cylindrical and about 

 once and two-thirds as long as the distal segment of the carjius and no 

 stouter. The third, fourth, and fifth peroeopods are nearly alike, and 

 about as long as the second ; the meri and propodi are subequal in 

 length, and the meri are armed with three to seven spines along the 

 distal part of the lower edge ; the lower edges of the propodi are 

 clothed with a few idumose hairs, and armed with several very slender 

 spines ; the dactyli are approximately a fourth as long as the propodi, 

 slightly curved, regularly tapered to an acute tip, and armed along the 

 lower edge with a regular series of si)inules. 



