DEVELOPMENT OF EUPHAUSIA SUPERBA 95 



distal segment of the palp (Fig. 23/) is longer and narrower than in the previous stage; 

 the number of spines borne on it varies as shown on p. 67. The labrum is shown in 

 Fig- 23 g. 



First maxilla. The palp and masticatory lobes of the ist maxilla (Fig. 23 h) have 

 more bristles than in the previous stage. The pseudexopod is now a conspicuous lamellar 

 structure completely covering the larval exopod, extending nearly to the insertion of the 

 palp and bearing a small bristle on its margin. The larval exopod is visible through the 

 pseudexopod. 



Second maxilla. The palp is now broader in proportion to its length and has more 

 bristles than in the previous stage (Fig. 23)). The exopod is more conspicuous and 

 furnished with about nine setose bristles. The two distal lobes on the inner margin 

 of this appendage have partially coalesced so that only four distinct lobes are now 

 apparent. 



First thoracic limb. The ist thoracic appendage (Fig. 24 rti) is still shorter than 

 Th. II. The exopod has a greater number of spines than formerly but has not yet as- 

 sumed the shape typical of the other exopods. 



Thoracic LIMBS II-VIII. The setae on Th. II-VI are more abundant (Fig. 24rtii,rtiv). 

 The vestige of Th. VII (Fig. 24bvn) bears a small spine and that of Th. VIII is a small 

 inconspicuous lobe set internally to the gill. In one very large three-spined larva 

 Th. VII was a conical process with a rounded tip bearing two small bristles and 

 Th. VIII a similar but smaller structure with one bristle. 



Gills. The gill on Th. I is rather fusiform in shape and attached, not at its end, but 

 at about one-third of the distance along one side (Fig. 24 6 i). The gills of Th. 1 1 and 1 1 1 

 are four-lobed, of Th. IV and V five-lobed, of Th. VI four-lobed, of Th. VII three- 

 lobed and of Th. VIII two lobed (Fig. 24 b ii-viii). In the last the two lobes are equal in 

 length and much larger than in the previous stage. In the very large three-spined larva 

 mentioned above the gill of Th. VII was four-lobed and that of Th. VIII three-lobed. 



Pleopods. There is nothing to distinguish the pleopods (Fig. 24 c i, c ii, c v) from those 

 in the previous stage except the number of setae which has increased so that there 

 are now typically fourteen to sixteen on the exopods. 



Table XXXVI records the occurrence of larvae with two terminal spines on the 

 telson. This is the last of the aberrant telson forms. In its infrequency it is consistent 

 with those which preceded it mentioned above on pp. 88 and 92. 



Table XXXVI. Occurrence of Fur cilia larvae with two terminal spines on telson 



