28 



DISCOVERY REPORTS 



A plankton sample from the north Atlantic (49° 53' N, 1 1° 3' W) contains Elaphocaris 

 of hispida type and a number of specimens of Acanthosoma which, apart from a small 

 difference in the uropods, agree with those of S. robnstiis. As this sample contains only 

 larvae of this species and of S. arcticiis we are satisfied that the Elaphocaris of hispida 

 form may be accepted with confidence as that of S. robustns. We have from Bermuda 

 (1939) another form of Elaphocaris which is evidently closely related but differs markedly 



Fig. 20. S. robustns. a, Elaphocaris 2; 6, Elaphocaris 3. 



in the shortness of the telson branches. This no doubt belongs to one of the forms of 

 Acanthosoma described below. As only one of these (Form D) was taken at Bermuda 

 it may provisionally be attached to that species. The first Elaphocaris was, in this case, 

 moulted to second, so that the sequence of stages is securely established. 



Description. Elaphocaris 2 (Fig. 20 a). Length 1-17 mm. Rostrum 0-92 mm. 



Rostrum with long spinules at base. Lateral process long, directed backwards at angle 

 of about 50° with middle line, very prickly. There is a slight swelling at the base which 

 bears a number of long spinules. Posterior process extending beyond end of body, with 



