EXPEDITION ANTARCTIQUE BELGE 



than sixth segment, widening from the base to near the end where it is almost twice as broad 

 as at the base ; a latéral spine is found somewhat behind the middle, and thèse spines hâve 

 each two secondary spinules at some distance from the base. The posterior margin has its 

 major portion straight, transverse, with seven spines ; towards each side the margin bends 

 suddenly obliquely forwards, and each oblique postero-lateral part has three spines. The seven 

 spines hâve a row of fine spinules along each margin ; the médian spine is moderately short, 

 while the others are gradually longer outwards, those of the fourth pair being not full\ T twice 

 as long as the médian spine. The three pairs of postero-lateral spines are characteristic ; the 

 inner spine is very long, a little longer than the next and nearly twice as long as the third 

 which is almost as long as the outer pair of posterior spines described ; ail three pairs hâve 

 at a good distance from the tip a small, conspicuous, dorsal spine, and the two long pairs 

 hâve numerous spinules along the inner margin between its base and the dorsal spine men- 

 tioned, while their outer margin is glabrous ; the shorter outer pair hâve only one or two 

 spinules on the inner margin. 



Stage B (figs. \f- — 4 //). — The spécimen drawn measures 6 mm. Céphalothorax, eves 

 and antennae nearly as in stage A. The process on the basai antennular joint does not reach 

 the end of the third joint; the flagella are subequal in length and a little longer than the third 

 joint, but still unjointed (fig. 4/). The mandibular palp is moderately short, nearly sausage- 

 shaped, scarcely divided into joints and without setse. The maxillipeds hâve the endopod 

 nearly twice as long as the exopod, three-jointed. The five pairs of legs hâve the endopods 

 distinctly divided into the final number of joints and are furnished with setae ; the four anterior 

 pairs are nearly twice as long as the maxillipeds, fifth pair are a little shorter ; the branchiae 

 are feebly developed. Ail pleopods hâve the exopods long and furnished with setae ; the endopods 

 are small. Sixth abdominal segment (fig. 4^) about half as long again as broad, the uropods 

 slightly more than half as long as the telson, not reaching its latéral spines, and the exopod 

 longer than the endopod. The telson is not three times longer than the sixth segment and 

 not fully three times as long as broad, thus conspicuously narrower than in stage A, but 

 the armature and relative length and breadth of its spines are nearly as in that stage. 



Stage C (fig. 4/). — A spécimen measures 7 mm. The rostral plate is a little narrower 

 than before ; the eyes are well marked off from the stalk. The inner antennular flagellum is 

 slightly shorter than the outer, as long as the sum of the two distal joints of the peduncle ; 

 both flagella are indistinctly divided into joints. The rami of the antennae are still subequal in 

 breadth, but the exopod is a little shorter than the endopod. The mandibular palp is three- 

 jointed, with a terminal bristle. The maxillipeds hâve the endopod somewhat longer than in 

 the preceding stage, but it has not acquired its full number of joints and is much shorter than 

 first pair of legs. The five pairs of legs look essentially as in the adults, the first pair reaching 

 the end of the second antennular joint, the fifth pair (in which the part beyond the fourth joint 

 is still rather short) having their end situated vertically below the posterior half of the eyes, but 

 the branchiae are still somewhat feebly developed. The pleopods hâve the endopod considerablv 

 longer than in the preceding stage, but still only half as long as the exopods. Sixth abdominal 

 segment and telson as to shape intermediate between stage B and stage D ; the uropods reach 

 to the latéral spines of the telson, and their rami are equal in length. The telson (fig. 4 i) has 

 still seven spines on the posterior margin, but they differ less from each other as to length. 

 The three postero-lateral spines hâve still preserved their armature, but the inner spine has 



