DEVELOPMENT OF EUPHAUSIA SUPERB A 87 



The carapace is, with minor modifications, as in the previous stage (Fig. 20 a). The 

 posterior margin is more concave and the rostrum sUghtly more elongate (Fig. 20 b), but 

 the latter is still rounded anteriorly except for a minute spine which may or may not be 

 present on the apex of the anterior border. 



The telson is seven-spined terminally and has the modification (Fig. 20 c) of the 

 postero-lateral spine just mentioned. The length of the telson is about 2,3 times the 

 width. The uropods extend beyond the lateral spines of the telson and are more setose, 

 having in the specimen figured thirteen setae on the outer ramus and twelve on the 

 inner (Fig. 20 d). 



Antennule. The flagella of the antennules are multi-articular: in the specimen 

 figured five segments are found (Fig. 20 b). They are roughly equal in length to the two 

 distal peduncular segments. The spine on the outer margin of the basal peduncular 

 segment is shorter than in the preceding stage, extending not more than about two- 

 thirds of the length of the distal peduncular segment (Fig. 20 e). 



Antenna. The antennae are still unchanged. 



Mandible. The palp (Fig. 20 f,g) is three-segmented with a long terminal spine. 

 The variations in form of this appendage in this stage are dealt with in another section 

 (p. 65). The lacinia mobilis is still present with fine hairs surrounding the base. 



First maxilla. The palp of the ist maxilla is unsegmented and has two extra bristles 

 on the inner margin, making seven bristles in all. The outer masticatory lobe in the 

 specimen examined has nine marginal and two submarginal bristles. The inner masti- 

 catory lobe has ten bristles, five of which are heavily setose and more robust, the re- 

 mainder slighter, smaller, and only finely plumose. The exognath is unchanged. The 

 divisions separating the ist and 2nd segments of the protopodite (sympod) cannot be 

 distinguished in this or in earlier stages, although a suggestion of such segmentation was 

 indicated in the 3rd Calyptopis. 



Second maxilla. The 2nd maxillae are unchanged. 



First thoracic limb. The endopod of this appendage is definitely five-segmented, 

 armed with numerous bristles and about three times as long as the exopod (Fig. 20 Ii). 

 The joint between the basal segment and the ist endopod segment is very indistinct in 

 this as in all the other limbs. The exopod is still primitive in form, bearing four bristles 

 distally. 



Thoracic limbs II-VII. The thoracic appendages II-VI are proportionately more 

 elongate than in the previous stage. The exopods are rather longer in relation to the most 

 proximal segment of the endopod and more setose than in the previous stage. Only 

 Th. Ill has been figured to show the size compared with Th. I (Fig. 20 j). Th. II is still 

 very slightly shorter than Th. III-VI. Th. VII is represented by two portions made up 

 of a branchial lobe externally and a luminous organ internally (Fig. 20 k). There is no 

 trace of Th. VIII at this stage. 



Gills. The gill on Th. I is small and inconspicuous. Those on Th. II-V are trilobed, 

 having the central branch longer than the remaining two. The gill of Th. VI is bilobed 



