34 



DISCOVERY REPORTS 



S. robustus Form A 

 Discovery Stations 99, 100, 102, 276, 715. 

 Stage I. Length 4-45 mm. Rostrum 1-55 mm. 



General form as in S. robustus, but carapace with three pairs of marginal spines. 

 Telson with lateral spines in front of fork. Arms of telson with a series of five or six 

 spines on the inner margin. Eye apparently without papilla. Setose margin of uropod 

 about ih times as long as bare part. 



/ 



Fig. 26. 5'. robustus A. a, Acanthosoma 2; b, S. robustus B. Acanthosoma i. 



Stage 2 (Fig. 26 a). Length 5-9 mm. Rostrum 175 mm. 



Pleopods with small rudiment of endopod on 2-5. Setose part of uropod about equal 

 to bare part. 



Mastigopus. The Mastigopus is scarcely distinguishable from S. robushis. The telson 



is shown in Fig. 27. 



S. robustus Form B 

 Discovery Stations 708, 711. 



Acanthosoma i (Fig. 26 b). Length 3-2 mm. Rostrum 1-2 mm. 



Basal spine of rostrum minute. Carapace a little longer than wide (3-6: 3-0) with two 

 pairs of lateral spines, of which the posterior one is a mere point. Supraorbital and 

 posterior dorsal spines very short. Lateral spines of somites 1-3 very much shorter 



