20 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



Fig. 23.— Dis- 

 cerceis lin- 

 guicauda. 

 Abdomen. 



Head subtriangular in shape; frontal margin with a small median 

 point; eyes po.st-laterally situated. The first pair of antenna? reach 

 the posterior margin of the iirst thoracic segment; the 

 second pair touch the fourth segment. 



The iirst segment of the thorax is a little longer than 

 an}' of the others, which are similar in size. The epimera 

 are not distinct from the segments, and are produced 

 into acute points, with the exception of the last segment, 

 which has the epimera quite rounded. 

 The abdomen is composed of two segments, the first of which gives 

 indication of three coalesced segments, and has a small tooth on each 

 side on its post-lateral margin. The la.st segment is 

 swollen anteriorly, and bears three low tul)crcles 

 on this portion. The extremity of the abdomen is 

 marked by a sinus, which is almost completely filled 

 by a single large tooth, which is posteriorly triangu- 

 lar and extends beyond the lateral teeth formed by 

 the sinus. This central tooth bears a small, pointed 

 tul)ercle near its base. The branches 

 of the uropoda are strongh' unlike; 

 the iiHier branch is short, rudimen- 

 tar}'; the outer branch is slighth' in- 

 curyed and is somewhat longer than 

 the abdomen. 



Tiie color is a dull yellow. The lower part of each 

 thoracic segment is densely granulated as well as the 

 whole surface of the abdomen. The edges of the segments and the 

 uropoda are fringed witii hairs. 

 The only specimen is a male. 



Genus CASSIDIAS, new genus. 



]VIouth parts of female metamorphosed. Seyenth segment of thorax 

 not produced backward in any process. 



Abdomen composed of two segments, the first of which is not pro- 

 duced backward in a median process. Terminal abdominal segment, 

 with a narrow notch, which is sometimes coi^cealed dorsall}', but a 

 groove is formed beneath by the infolding of the margins. 



Both i)ranches of the fourth pair of pleopods are similar, fieshy, 

 with transverse folds and without marginal seta?. The exopod of the 

 the third pleopod is two-jointed. 



The branches of the uropods are similar, the outer one being capable 

 of folding under the inner one. 



This genus is nearest to Cassidinojms Hansen than to any other genus, 

 but diflers in ha^'ing the mouth parts metamorphosed in the female 

 and in havinsf the head of normal size. 



Fig. 24.— Discerceis 

 i. i n g u i c .\ u d a . 

 Third PLEOPOD. x52. 



Fig. 25.— Discer- 

 ceis LINGUICAUDA. 



Fourth pleopod. 

 X 52. 



