LARVAE OF SERGESTES 59 



There are differences in form of telson and uropod between these specimens and the 

 figures given by lUig, and he does not mention ventral abdominal spines ; but otherwise 

 the agreement is close. 



Remarks. While of the same general form as the larva of S. vigilax the Acanthosoma 

 described differs from it in nearly all details, particularly in the large size and long 

 spinules of the lateral thoracic spines, and the longer dorsal spines of the abdomen. 

 Both have ventral spines on abdominal somites i and 2. We have the authority of 

 Hansen for regarding S. penerinkii Bate as the Mastigopus of S. diapontms, and he also 

 confirms the presence of ventral spines on somites i and 2. We regard this particular 

 feature as the strongest reason for reference of the Acanthosoma to S. diapontius. 



We have not seen any Mastigopus which can be referred to this species. According 

 to Hansen and lUig it resembles S. vigilax very closely. According to Hansen it differs 

 from the latter in retaining the dorsal spines on abdominal somites 3-5 up to a length 

 of 14 mm. The rostrum is said to be longer at equivalent stages, and the eyes shorter 

 and with smaller eyeballs. These differences do not appear in Illig's figure of a Mastigopus 

 of 5 mm. (Fig. 117) which lacks the ventral abdominal spines and has eyes as long and 

 as large as S. vigilax. 



Sergestes armatus Kroyer 



Hansen, 1922, p. 179, Mastigopus. 



Illig, 1927, fig. 126, Elaphocaris 2 (?). 



Cecchini, 19286, p. 41, Mastigopus. 

 Material. This appears to be a rare species at Bermuda. The characters of Elapho- 

 caris 3 have been established by moult to Acanthosoma, but Elaphocaris i and 2 

 described below are referred to this species with some doubt since, though stage i was 

 connected with stage 2 by moult, stage 2 was not so connected with stage 3 . The difference 

 in structure of the posterior process makes the identification doubtful, but the similarity 

 in colour is very close, and it is difficult to suggest any other species to which these stages 

 could belong. The first Mastigopus was obtained by moult from the Acanthosoma. The 

 Acanthosoma was found also at Discovery Stations 701 and 703. 



Description. Elaphocaris i (Fig. 52 a). Length 0-56 mm. 



Anterior process with a pair of large lateral spines near base and a pair of smaller 

 ones beyond. Lateral process almost at right angles to carapace and curving backwards 

 at end, nearly smooth. Posterior process rather short, with two pairs of spines. Telson 

 branches very long and slender ; spine 5 not greatly longer than the others. Labral spine 

 unusually long. 



Elaphocaris 2 (Fig. 52 b, c). Length 07 mm. Rostrum 0-96 mm. 



Rostrum very long and stout, with three pairs of lateral and two dorsal spines. 

 Lateral process with four pairs of lateral spines. Posterior process swollen at base where 

 it bears eight spines. 



Colour. A large patch of crimson in gastric region. A fleck of red in the black pigment 



of the eye. 



8-2 



