LARVAE OF SERGESTES 



29 



a group of long spinules at base, but not swollen. Dorsal organ not seen. Telson arms 

 almost at right angles to body line, long and slender. 



Eye small, pear-shaped, with small anterior ventral papilla and without pigment (in 

 formol). 



Elaphocaris 3 (Fig. 20 b). Length 2- 16 mm. Rostrum 1-28 mm. 



Rostrum without long spinules at base. Supraorbital spine longer than eye. Lateral 

 process as in stage 2, with swollen base. Posterior process not reaching end of body. 

 Dorsal organ very small. Telson as in stage 2. 



Eye large, about one-quarter length of body, the diameter of the eyeball about half 

 length of eye. 



Acanthosoma i (Fig. 21 a-c). Length 4-0-4-45 mm. Rostrum 1-5 mm. 



Rostrum nearly as long as thorax. Carapace nearly twice as long as wide. Supra- 

 orbital spines shorter than eyes, with very small spinules. Hepatic spines large. Two 

 pairs of lateral spines, of which the posterior is the 

 smaller, with small spinules. Posterior dorsal spine short. 



Abdominal somites with dorsal spines of somites 

 I and 2 small, those of 3-6 larger; lateral spines very 

 long, those of somite 5 the longest, and directed back- 

 wards at angle of 45°. Ventral spines absent. Telson 

 twice as long as wide, with long lateral spines inserted 

 at base of telson fork. The position of the lateral spine 

 is somewhat variable, but it is always close to the fork. 

 Arms of apical fork very long, slender, parallel at first 

 and diverging towards end. Each branch has two inner 

 and two outer marginal spines. Antennal scale of much 

 the same shape as in S. tenuiremis, with five apical setae 

 and one small outer seta; flagellum about i\ times as 

 long as scale, with marginal spine at base and near end. 



Eye very long and slender, about one-sixth length 

 of body, the eyeball round, its diameter less than half 

 length of eye. There is a small papilla on eyestalk. ^ 

 Mandible without palp. Pleopods small, without endo- 

 pods. Uropods about seven times as long as wide, with 

 very large outer spine ; setose part of margin about equal eye, showing papilla, 

 to bare part. 



Acanthosoma 2 (Fig. 22 a-b). Length 5-0 mm. Rostrum 2-0 mm. 

 General form as in stage i. Antennal scale long and slender but widening distally, 

 and with very long apical spine. Flagellum about half length of body. Branches of 

 telson with two outer and two inner spines. There may also be a very small inner spine 

 near base of arm. Exopod of uropod broad, about six times as long as wide, with strong 

 marginal spine dividing outer margin into nearly equal portions. Pleopods long, 



Fig. 21. S. robust us. Acanthosoma i. 

 a, b, flagellum and scale of antenna; c, 



