ECHINODERMATA OF NEW ENGLAND. 9 



the diameter of the ring of wire possibly twenty inches. 

 The wire should be large enough not to be bent under a 



O O 



considerable strain. 



Three pieces of line about the size of cod-line and about 

 two feet long are fastened at equal intervals in the ring. 

 These are all joined at one end and attached to the tow- 

 ing-line. Enough of the towing-line should be let out to 

 cause the net to work just below the surface. The length 

 of the towing-line must be learned from experience. 



The towing apparatus, thus rigged, is used in the fol- 

 lowing way : After the net is thrown over the stern of 

 the boat, a moderate headway is given to the boat. The 

 length of time the net must be dragged is regulated by the 

 abundance of surface life. Care should be taken that the 

 headway of the boat is not lost, as in such a case the ani- 

 mals are washed out of the net. To obtain life from zones 

 below the surface the net can be weighted by a weight de- 

 termined by the length of the tow-rope, the velocity of the 

 boat and other circumstances. Care should betaken, if 

 the direction of headway is changed, that the net is always 

 kept distended in its original direction. When there is a 

 coastward current under a bridge, the towing-line may be 

 fastened to the bridge and the force of the current utilized 

 to distend the net. 



a. Freeing the net of its collections. 

 The net is hauled on board and the contents simply 

 washed into a pail of pure water by turning the net wrong 

 side out. An ordinary water bucket is a good collecting 

 vessel. For detection of the specimens the best plan is to 

 use glass vessels over a black ground. Mr. A. Agassiz uses 



O O O 



flat glass pans over a table of black tiles. Altaian recom- 

 mends a white glazed earthenware pan such as is used in 

 dairies for holding milk. If the bowl is placed in a deep 



K3S3X IX ST. BULLETIN, VOL. XXIII 1* 



