644 CRUSTACEA. 



articulated with the obliquely truncate apical margin, just under the 

 apex, which is acute. The branches of the third pair are similar to 

 one another though unequal in size. 



At the base of each of the anterior four abdominal legs, between 

 the two legs of each pair, there was a ruby-red, shining globule ; also, 

 one on each side at base of sixth and second pairs of thoracic legs ; 

 also a large red, or brownish red spot in the back, not far from the 

 eyes. Several individuals were observed to emit light, and it was 

 seen to come from the anterior part of the cephalothorax. The light 

 was intense and had a greenish tinge. 



EUPHAUSIA GRACILIS. 



Carapax brevissime rostratus. Articulus antennarum iniemarum primus 

 ad apicem parce productus et acutus. /Squama basalis antennarum 

 externarum basin rnulto superans. Pedes tenuissimi, articulis tribm 

 ultimis submquis simulque sumtis precedente vix brevioribus, setts h/t- 

 giusculis, palpo parvulo, quadruplo breviore. Segmentum abdominis 

 posticum lamellis caudalibus non longius, Gtum btofere duplo longius. 

 Branchim posticai ramosw. 



Carapax very short rostrate. First joint of inner antennae sparingly 

 produced and acute at apex. Basal scale of outer antenna? longer 

 than base. Feet very slender, last three joints subequal, and to- 

 gether but little shorter than preceding joint, seta* longish, palpus 

 quite small, about one-fourth as long as leg. Last abdominal seg- 

 ment not longer than caudal lamella?, sixth segment about twice as 

 long as fifth. Posterior branchia? ramose. 



Plate 42, fig. 6 a, animal, enlarged; b, extremity of abdomen (setules 

 of apex probably lost by mutilation) ; c, posterior branchia. 



Pacific, latitude 15° 23' south, longitude 148° 23' west. Caught 

 one individual during a calm at 4 A. m., September 10, 1839. 



Length, half an inch. Colour, reddish along the venter and in the 

 legs. Scale of second antenna; extends beyond apex of base about as 

 far as length of penult joint of base. The last abdominal segment 



