EXPEDITION ANTARCTIQUE BELGE 



The antennulse hâve the process of first peduncular joint very long, reaching almost to the end 

 of the peduncle ; the flagella are extremely long, measuring 2.4 mm., not fully two and a half 

 times as long as the peduncle, subequal in length and distinctly jointed. The antennse hâve the 

 endopod more than twice as long as the exopod, sausage-shaped, unjointed ; the exopod has 

 to a certain degree acquired the final shape with setae along the inner and the terminal margin. 

 The mandibular palp is moderately short, feebly jointed, without bristles. 



The maxillipeds and anterior pair of legs essentially as in the adults ; third pair are 

 somewhat shorter, fourth pair hâve the endopod only half as long as in the third pair, and the 

 endopod of fifth pair is very short, nearly rudimentary. The pleopoda developed nearly as in 

 stage D of E. superba. Sixth abdominal segment slender, more than twice as long as broad. 

 Telson slender, four times as long as broad ; the degree of development and armature nearly 

 as in E. superba stage C, and small spécifie différences in the spines may be seen on the figures. 



Stage B (figs. 1 d — 1 /). — Length of one ofthe two spécimens 8.8 mm. The armature of 

 the telson is less reduced than in stage D of E. superba, but in several other characters the 

 animais are much more developed. The antennulœ hâve still the process from the basai joint 

 nearly as long as the two following joints ; the flagella are long, but their terminal part is lost. 

 The antennaa hâve both the squama and the flagellum sh'aped nearly as in the adult. The 

 mandibular palp is three-jointed, with a very long terminal seta. Fourth pair of legs still 

 considerably shorter than second (third pair are lost), and fifth pair are nearly rudimentary. 

 Sixth abdominal segment somewhat more than twice as long as broad (fig. 1 e) ; the uropoda 

 reach a little beyond the latéral spines ofthe telson. The telson is slightly more than twice as 

 long as the sixth segment and five times as long as broad, thus very narrow ; the posterior 

 margin is a little shorter than in stage A and its latéral pair of spines are somewhat reduced in 

 size (fig. 1 /) ; the postero-lateral margins are considerably longer than in stage A and besides 

 considerably concave ; the inner spine has its proximal third fiât and very expanded ; both this 

 spine and the next are much longer than in stage A while the outer spine has its former length. 



Judging from many particulars I think that the two stages (three spécimens) described 

 belong to the same species, but I am not able to point out the adult species to which thèse larv?e 

 belong. The length of the process of the basai antennular joint, the high development of the 

 antennular flagella and the slenderness of the abdomen ma}- induce one to refer them to 

 E. crystallorophias, but a comparison between stage B and the above-mentioned animais referred 

 to E. crystallorophias shows that the eyes are considerably smaller in the larvae of stage B than 

 in the last-named animais, though they differ little from each other in length, and the différence 

 as to the eyes is so considérable that the référence to E. crystallorophias must be abandoned. 



Localities. — Lat. 70 41' S., long. 90 14' W., Ma)* 1, 1898, plankton ; one spécimen 

 (stage A). — Lat. 7i°i5' S., long. 87 27' W., May 21, 1898, plankton; two spécimens (stage B). 



D. — SOME MORPHOLOGICAL REMARKS ON THE DEVELOPMENT 



IN EUPHAUSIA 



It is pointed out in the description of stage A of Euphausia sp. that this larva has the 

 telson developed as stage C of E. superba, while its antennular flagella is widely more developed, 



