EUEOPEAlSr FORMS OF THE CIEOLANINjB. 351 



Eyes moderately large, black, seen from the side longer than 

 deep, with the upper margin slightly convex. 



Frontal plate small, pentagonal, at most one half as long 

 again as broad ; its front end acute, not visible from above. 

 Clypeus without any anterior process ; its surface slightly 

 convex, with a furrow along each lateral margin. 



Antennulse about as long as the peduncle of the antennae ; 

 flagellum moderately slender, with about fifteen joints. 



Antennae long, reaching much beyond the middle of thorax ; 

 flagellum with numerous, sometimes even more than forty, 

 joints. 



Epimera of the thoracic segments increase gradually in size 

 backwards; each has a deep oblique furrow besides tbe sub- 

 marginal one. 



Seventh thoracic legs without natatory setae but with numerous 

 simple, acute spines, and some very short hairs ; second joint very 

 robust, twice as long as broad ; fourth joint a little shorter than 

 fifth, which is somewhat shorter than sixth. 



Last abdominal segment subtriangular, posteriorly rather 

 narrowly rounded, with four to six pairs of marginal spines. 



Uropoda rather broad. Endopod, when directed parallel with 

 the axis o± the animal, reaches considerably beyond the end of 

 abdomen ; it is from a little less (in small specimens) to a little 

 more (in large specimens) than twice as long as broad. Exopod 

 about three times as long as broad, somewhat shorter than the 

 endopod. 



Differences according to Age. — Large, and especially very large, 

 specimens differ from smaller ones in shape and clothing of last 

 abdominal segment and uropoda. In smaller specimens the 

 upper surface of this segment is distinctly convex, glabrous, or at 

 most with a number of nearly inconspicuous elevated points, while 

 the distal half of the lateral margins is feebly convex or at most 

 straight. In large, and especially in very large, specimens a 

 large portion of the upper surface is flat or even slightly depressed, 

 adorned with numerous conspicuous elevated points ; the distal 

 half of the lateral margins is a little concave, wherefore the 

 corresponding part of the segment is more narrow than in young 

 specimens. The uropoda show the following differences. In 

 smaller specimens the outer margin of the endopod is rather 

 regularly but feebly convex and the end acute ; on both rami the 

 clothing of setae is of normal density on both margins, so that 

 all marginal spines are easily seen. In large, and especially very 



