NATURAL SCIENCES OF PHILADELPHIA. 



395 



1897.] 



length in a large specimen and have a ten-jointed flagellum ; the 

 distal joint of the peduncle is 1.5 mm. in length. The outline of the 

 thorax is ovate in both sexes; the undulations are distinct; the 

 fourth segment is the longest. The epimeral sutures of the three 

 posterior segments can be made out under a lens. The incisions on 

 the sides of the abdomen are short ; the areolations at the base and 

 summit are large and smooth. The lateral outline of the anterior 

 half is straight or slightly concave, of the posterior half convex. 

 The distal end is slightly excavated. 



Several specimens of both sexes were taken at Station 3,600 in 

 company with S. picta, and at Station 3,637 in 32 fathoms. Mr. 

 Dall obtained them at Unalaska in 16 fathoms ; at Kyska Harbor, 

 9 to 16 fathoms; Semidi Islands, 12 to 25 fathoms. Types (No. 

 20,503, U. S. N. M.) from Station 3,600, lat. N. 55° 06' 00", Ion. 

 W. 163° 28' 00", 9 fathoms. 



This species can be distinguished at sight from all other alcoholic 

 specimens of the genus by its dark-colored head and fourth segment, 

 and by the dark line surrounding the elevated portions of the abdo- 

 men. The first and last three segments of the thorax are light with 

 small flakes of black uniformly sprinkled over the surface; the 

 median line of the first three is usually broad and dark. 



Length of a large male, 17 mm. ; width, 6.5 mm. Length of a 

 large female, 15 mm. ; width, 7 mm. 



Synidotea angulata, new species. Fig. 6. 



This is a small species easily distin- 

 guished from the others of the genus in 

 its region by the angular and projecting 

 lateral margins of the first three thoracic 

 segments ; it is most nearly related to S. 

 nebulosa. 



The head is excavated in front in a 

 nearly even curve, and there is no dis- 

 tinct median notch as in nebulosa. Be- 

 tween the eyes and the front the tuber- 

 cles are very low and inconspicuous ; 

 the cross areolation is a low ridge inter- 

 rupted in the middle by a V-shaped 

 notch ; the lateral areolations of other 

 species, in this, form a single transverse 

 areolation not at all separated in the middle ; it is separated from 

 the postcephalic lobe by a deep impression. The sides of the head 



Fig. 6. Synidotea angulata 

 Benedict, x ♦. 



