Marine Copepoda 



37 K 



the caudal setae, although a figure by Sars shows them slightly enlarged. A 

 similar condition, again, still more pronounced, is figured by Sars for Amphiascus 

 giesbrechti, but here the protuberance (s directed outwards. 



Whatever may be the significance of this small tubercle on the caudal setae, 

 it is of some interest to find it occurring in three different genera. 



29. Amphiascus nasutus (Boeck). 



Station 4 In. See under Dactylopusia signata. 



Station 43e. See Table VII. 



This is, for its size, a stout harpacticoid with heavily built cylindrical 

 urosome. Length of female, 1-22 mm., of male, 0-72 mm. Caudal ramus 

 truncate, shorter than anal segment (Fig. 53). 



Fig. 53. Amphiascus nasutus. 

 Anal segment and furca from below. 



Anterior antennae distinctly 9-jointed, the proportional lengths of the 

 joints being: 7, 5, 5, 7, 2, 3, 1-5, 2, 4. Posterior antennae with Re three-jointed, 

 the middle joint short; Re 1 with one seta, Re 2 achaetous, Re 3 with one 

 proximal and two strong apical setae with several setules around their bases. 

 Second maxilliped with the si of the hand arising towards the distal end of the 

 joint. 



Thoracic legs: p 1 with both rami three-jointed as in Dactylopusia, but 

 the si of Ri 1 is inserted near the distal end of the joint (Fig. 54). 



Fig. 54. Amphiascus nasutus. P 1. 



In the second leg (p 2), Ri 2 has two setae, Ri 3 has only four (1 se, 3si), in 

 place of the five in Dactylopusia (Fig. 55) ; B2 has a slender se and a short thorn- 

 like process in place of an si; outer distal angles of Re 1 and Re 2 are produced 



