THE PELAGIC TUNIOATA. 201 



Sta. 12 A.A., Sept. 4, 1899, Lat. N. 10' 54', Long. W. 137' 35'. Fifteen 

 specimens of the aggregate generation were collected on the surface. 



Their ridges are only slightly serrate. 



Stn. 14 A.A., Sept. 7, 1899, Lat. N. 6" 41', Long. W. 137°, surface temp. 

 82°. A single specimen of the solitary generation was taken on the surface 

 at 8 p. M. 



Pyrosoma giganteum Les. 



Stn. 3474, Dec. 6, 1891, Lat. N. 21' 12', Long. W. 157° 38' 30", 

 Hawaiian Islands. Surface temp. 77 . Two specimens measuring respec- 

 tively 8 cen. long and 5 cen. broad at closed end and 2 cen. broad at open 

 end ; and G cen. long and 2.5 cen. broad at open end ; .9 cen. broad at closed 

 end ; colony narrowing abruptly toward closed end. 



Pyrosoma atlanticum. 



Stn. 14 A.A., Sept. 7, 1899, Lat. N. 6' 41', Long. W. 137°, surface temp. 

 82°. Fourteen specimens were talven in the surface tow-net at 8 i". M. The 

 largest measures 11.8 cen. in length, 2.7 cen. in greatest breadth, 2.4 cen. at 

 the open, and 1.3 cen. at the closed end. The smallest measures 5.5 cen. in 

 length, 13 cen. greatest breadth, .9 cen. at open, and .6 at closed end. All 

 are of a beautiful clear shining white color. 



Pyrosoma agassizi, sp. nov. 



External Characters. Colony cylindrical, flaccid, 12 cen. long, 1 cen. 

 broad in the middle, tapering very slightly toward both extremities. . Sur- 

 face covered with small quadrangular processes, 1 to 5 mm. in length, 

 tapering abruptly from a broad base to an acute point ; all curving toward 

 the open end of the colony. Common atrial opening 6 mm. wide, guarded 

 by four large processes of the test. These processes 6 mm. long, non- 

 muscular, quadrangular, tapering to a ))lunt point; placed in pairs on 

 opposite sides of the opening over which they curve. Test between 



