FISHERY BULLETIN: VOL. 73. NO 1 



next molt. A few of the details which helped 

 to clarify the relationship between furcilia with 

 variant forms are noted in Table 3. 



The total number of dominant and variant 

 forms of furcilia IV- VI in samples examined and 

 the percentage of each form within these stages 

 is given in Table 4. The potential variation in 

 reduction of the number of terminal telson spines 

 was estimated by counting the number of spines 

 developing on the telson of the next instar 

 when possible. The range observed in each form 

 is shown in Table 4. 



John (1936) in describing larvae of species of 

 Euphausia from the Southern Ocean noted that 

 the "furcilia stages recognized by the number of 

 terminal spines on the telson are not such 

 natural groups as those recognized by the char- 

 acter and number of the pleopods"; this appears 

 to be true as well for E. gibboides. As observed 

 in other species (Mauchline and Fisher 1969), 

 there is a general correlation between size of 

 furcilia and the number of terminal telson spines 

 (Tables 7, 8). As the larvae become larger, on 

 the average, the number of spines usually de- 

 creases, and stages may be characterized by size, 

 number of spines, and relative abundance. 

 Furcilia identified by a vdder range of develop- 

 mental details, however, seem to be grouped 

 more naturally. 



Description of Stages 



Nauplius I (Figure lA) 



Body egg-shaped, with 3 pairs of appendages. 

 Antennule (Figure 6A) uniramous, unseg- 



Table 4. — The number of dominant and variant forms of 

 furcilia IV, V, and VI observed, the percentage of each form 

 within stage, and the variation in number of terminal telson 

 spines on developing telson of next instar among individuals 

 of each form. 



mented, with 1 seta and 2 small spines termi- 

 nally, and 1 small subterminal spine. 



Antenna (Figure 7A) biramous, unsegmented; 

 exopod with 4 setae and tiny tooth distally; 

 endopod with 2 setae and small spine terminally 

 and 1 subterminal seta. 



Mandible (Figure 7G) biramous, unsegmented; 

 endopod and exopod each with 3 setae. 



Nauplius II (Figure IB) 



Body longer, with 2 pairs posterior spines, outer 

 pair very small. 



Antennule (Figure 6B) with 2 setae and 1 spine 

 terminally, and a small subterminal spine. 



Antenna (Figure 7B) with 5 setae and some- 

 times a rudimentary 6th seta on exopod. Endopod 

 with 3 setae and a small spine terminally, and 

 1 subterminal seta. 



Mandible as in nauplius I. 



Metanauplius (Figure IC, D) 



Carapace produced into wide rostral hood 

 fringed with marginal spines; anterior margin 

 with 3 or 4 relatively long pairs interspersed; 

 posterolateral lobes curved ventrally around body; 

 dorsal crest prominent, without spines. Abdomen 

 short, posterior margin with median indentation 

 and 5 pairs of spines; 3rd pair relatively long bear- 

 ing setules, other pairs small and fused with 

 telson, one or both of inner pair sometimes 

 rudimentary. There are only 2 pairs of func- 

 tional appendages. 



Antennule (Figure 6C) with 2 setae, 1 aesthe- 

 tasc (sensory seta), and 1 spine terminally and 

 a small subterminal spine. 



Antennal exopod and endopod (Figure 7C) 

 articulated with basal segment which may show 

 incipient segmentation. Exopod with 6 setae on 

 5 small distal segments; terminal segment, too 

 small to be visible in figure, bears 2 setae. 

 Endopod with 4 setae and 2 small spines distally 

 and 1 subterminal seta on inner margin; rudi- 

 ment of proximal 2nd marginal seta sometimes 

 present. 



Mandibles, maxillules, maxillae, and maxilli- 

 peds present as rudimentary buds. 



Calyptopis I (Figure 2A-C) 



Carapace with distinctive broad rostral hood 

 fringed with small marginal spines; lateral 



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