KNIGHT: LARVAL DEVELOPMENT OF EUPHAUSIA EXIMIA 



Table 6. — Setation of pleopods in the northern form of Euphausia eximia; = usual condition. 



'In juvenile I, 11, 13, and 7% of pleopods 1,2,and3with 1 seta proximal to appendix interna on endopod in 30 individuals. 



specimens). Small pair of papillae on anterior 

 margin of body beneath carapace; Fraser (1936) 

 described papillae as frontal sensory organs. 



Antennule and antenna functional, mandible 

 reduced, buds of maxillule, maxilla, and maxil- 

 liped present. 



Abdomen short, posterior margin with 5 pairs of 

 spines; relatively long third pair articulated with 

 telson, shorter spines fused. The long spine is 

 plumose in E. gibboides but appears nearly 

 smooth (with tiny serrations sometimes visible) in 

 E. eximia. 



CALYPTOPIS I (FIGURES 2B, 3B).— Rostral 

 hood of carapace fringed with spines curving me- 

 dially on anterior margin and posteriorly on pos- 

 terolateral curve of hood; posterior margin of 

 carapace produced into small dorsal spine; dorsal 

 crest without spines. Striated body of photophore 

 visible in developing compound eye, ocular papil- 

 lae situated medially slightly below anterior mar- 

 gin of eye. 



Mandibles (Figure 4a) with asymmetrical me- 

 dian armature and with anterolateral process but 

 without lateral knob seen in species of the E. gib- 

 boides group (lateral knob is not found in any 

 stage of £. eximia); anterolateral process, repre- 

 senting palp (Gurney 1942), decreases in size until 

 furcilia V. 



Maxillule and maxilla functional. 



Maxilliped (Figure 5a) with form and setation 

 as in E. gibboides: coxa with 4 setae on inner 

 margin and 1 seta on posterior face; basis with 5 

 setae on inner margin and 1 distal submarginal 

 seta, 1 marginal seta noticeably stout; endopod 

 2-segmented, proximal segment with 3 setae, 2 

 marginal and 1 submarginal, 1 marginal seta 

 small and stout, distal segment with 4 terminal 

 setae; exopod with 4 terminal setae and 1 lateral 

 seta near articulation with basis. In E. gibboides 

 the stout setae of endopod segment 1 and basis are 

 nearly equal in length. 



Abdomen unsegmented. 



Telson (Figure 6a) with 1 pair lateral, 3 pairs 

 posterolateral, and 6 terminal spines, middle 

 posterolateral spine slightly longer than other 

 spines. 



CALYPTOPIS II (FIGURES 2C, 3C).— 

 Carapace with lateral margins of rostral hood 

 curved ventrally around body so that in dorsal 

 view marginal spines are visible only on anterior 

 margin of carapace. 



Maxilliped with stout seta of endopod segment 1 

 and basis now about equal in length, as figured for 

 calyptopis III (Figure 5b). 



Abdomen with 5 segments. 



Telson (Figure 6b) with 7 terminal spines, mid- 

 dle posterolateral spine relatively long, armature 

 of telson spines as in E. gibboides. 



CALPYTOPIS III (FIGURES 2D, 3D).— 

 Carapace still with marginal spines of rostral hood 

 visible in dorsal view only on anterior margin 

 which extends well beyond eyes; lateral margins 

 with denticle. Pigment sometimes visible in de- 

 veloping compound eyes; ocular papillae small, set 

 farther out on eyestalk. 



Maxilliped (Figure 5b) endopod with 5 setae on 

 terminal segment unlike species oiE. gibboides 

 group which retain 4 setae in this stage, coxa with 

 6 setae. 



Abdomen with 6 segments, sixth segment with 

 pair of biramous uropods. 



FURCILIA I (FIGURES 7A, 8A).— Carapace 

 wdth rectangular rostral plate fringed with mar- 

 ginal spines which curve toward small median 

 spine or denticle; posterior margin with dorsal 

 spine. Eyes movable, pigmented, with rounded 

 contour in furcilia stages (Figure 8d) unlike lobed 

 contour o^ E . gibboides eye. 



Bud of leg 2 present. 



Abdomen with one pair nonsetose pleopods on 

 segment 1. 



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