SERGESTES EDWARDSII. 213 



tapering anteriorly in the largest individuals to a slender acute point, which 

 overreaches the anterior margin of the ophthalmic segment. 



The abdominal somites are unarmed, rounded above, the third, fourth, 

 and fifth longitudinally sulcated on the dorsal face. The telson is sulcated 

 on the dorsum and on each side, and ends in a blunt, ciliated point. 



The eye-stalks are shorter than the proximal segment of the antennule ; 

 the eyes are black, and somewhat greater in diameter than the stalks. The 

 first and second segments of the antennule are of about equal lenti-th, while 

 the third segment is longer than the first or the second by one half The 

 second segment of the antenna of the second pair is armed with a small 

 external spine ; the scale is lanceolate, terminating in an apical spine ; it 

 falls short of reaching the distal end of the antennular peduncle. The 

 second and third pairs of niaxillipeds are robust organs compared with the 

 following thoracic appendages ; the second pair reach forward as far as the 

 distal end of the peduncle of the second antennae ; the third pair are equal 

 in length to the whole body, minus the telson and half the sixth somite ; the 

 distal part of these appendages is armed with spines of various lengths ; four 

 of these spines, one of which is terminal, are exceedingly long and acute. 

 The following pairs of thoracic appendages have the form characteristic of 

 the genus to which this species belongs. 



The petasma of a large male is figured on Plate LI., Fig. 1". 



The two branches of the last pair of abdominal appendages are longer 

 than the telson, the outer branch longer than the inner. The external 

 margin of the outer branch is not armed with a spine, but about one third 

 of the way from the proximal end this branch of the swimmeret suddenly 

 narrows by a change in the trend of the external margin. 



There are six large pleurobranchi* on each side of the body, two on the 

 thirteenth, or penultimate thoracic, somite, and one on each of the four ante- 

 cedent (ninth to twelfth) i^omites ; a smaller but perfectly formed podo- 

 branchia is attached to the base of the second maxilliped. 



Length of one of the largest specimens (Station 3388), 29 mm. ; cara- 

 pace, 9.3 mm. 



A good many specimens of this pelagic species were taken in tlie surface 

 tow-net and also in the upper, open part of the submarine tow-net at the fol- 

 lowing stations: hydr. 2619, hydr. 2627, hydr. 2628, 3382, 3388, 3409, 

 3412, 3414. 



Three laro;e males from Station 3388 (one of which is figured on Plnlc 



