LARVAE OF SERGESTES 



Group I 



Sergestes atlanticus H. M. Edw. 



Hansen, 1922, p. 47, Mastigopus. 



Illig/ 1914, P- 350, Acanthosoma 2 {S. ovatoculus). 



Material. Fairly common at Bermuda in water of 100-250 metres or more, the 

 Elaphocaris in the deeper layers. Moults obtained from Elaphocaris i to Elaphocaris 2 ; 

 from Elaphocaris 3 to Acanthosoma; and from Acanthosoma 2 to Mastigopus. 

 Elaphocaris 2 is presumed to belong to this series from similarity in colour^ and form of 

 posterior dorsal process. 



Acanthosoma and Mastigopus taken at Discovery Stations 701, 708, 709. 



b 



Fig. I . S. atlanticus. a, Elaphocaris i ; b, Elaphocaris 2 ; c, dorsal spine from side. 



Description. Elaphocaris i (Fig. i a). Length o-8 mm. 



Anterior process dividing into three equal denticulate spines. Lateral process curved 

 backwards, denticulate, and without spines. Posterior process about two-thirds length 

 of abdomen, denticulate, without spines. Telson branches long and narrow, the long 

 spines subequal. 



Elaphocaris 2 (Fig. i b, c). Length 1-3 mm. Rostrum 0-94 mm. 



Rostrum as long as carapace, with seven spines, rather irregularly arranged. Lateral 

 process with five anterior and four posterior spines. Posterior process swollen at base, 



1 We have in all cases omitted references which have already been given by Hansen. 



2 The colour is indicated by black or stippling in the figures. 



