24 Illinois Slate Laboratory of Natural History. 



Fig. 4. — Longitudinal section of plankton bucket. X 1. 



Fn;. 5.— Cross-section of plankton bucket at x-y, Fig. 4. X 1. Letter- 



Plate III. 



ing as in Fig. 4. 



Fig G. — Carriage, with suspended plankton 

 a b c. Line of separation of s. 



carriage. s.l.l,s.l 2,8.1.3. 

 /in. Bucket. 



c. r. Carriage rope. s. I. 4. 



d. I. Draw-line. sn. 

 h. Hook. th. 

 k. End knot. w. s. 

 I. Lead. w xy z. 



p. Front pulley. 

 p.' Hear pulley. 



Fk;. 7. — Operation of the oblique haul. X ; 

 h. r. Brace rope. e. s. 



b. s. Brace stake. in. 

 /it. Boat. m. s. 



c. r. Carriage rope befoi'e n. 



release. n.' 



c. r.' Carriage rope after r. I. 



release. sur. 



d. I. I ) raw-line. 



net. X i 

 Staple. 



Stay-lines from the draw 

 line to net and bucket. 

 Stay-line to carriage. 

 Snap. 

 Thread. 

 Wire stay. 



Screw-eyes for attach- 

 ment of net. 



sos- 

 End stake. 

 30-meter knot. 

 Main stake. 

 Xet before release. 

 Xet after release. 

 Release line. 

 Surface of water. 



Plate IV. 



FlG. 8. Plankton net used with the pump, shown in longitudinal 

 section. 



X >,. 



b. I. Butchers' linen. 



con. Connector. 



cov. Cover. 



f. Foot. 



.//. Float. 



h. Handle. 



i. c. Inner cone or spreader. 



i. n. Inner net. 



o. n. Outer net. 



p. Pivot for support of ring. 



ri. Ring for inner net. 



st. Stay for inner cone. 



(. I). Turn button. 



t. .*>•. Turn support. 



tr. Trough. 



w. Wins:. 



