4 Illinois State Lahoratory of Natural History. 



The average area of the openings is reported by Reighard 

 ('94, p. 57) to he: 



.00003596 sq. em. in the new cloth, 



.00002808 sq. cm. in cloth that had been wetted and then 

 dried, 



.00002836 sq. cm. in cloth that had l)een used for 40 

 hauls of a net. 



As the new silk shrinks consideral)ly after its first wetting, 

 we have followed the practice of thoroughly and repeatedly 

 sponging it and pressing it with a hot iron before cutting out 

 the net. Otherwise in a single-seam net there is sufficient 

 shrinkage to cause the filtering cone to take a position oblique 

 to the true axis of the net (See Apstein, '96, p. 34, Fig. 3). 



The following directions for making a pattern for the net 

 are here inserted, as they may be of use to those to whom the 

 original descriptions given l)y Apstein ('91, '92, and '96) are 

 inaccessible. 



C=lRvl 



FiK, A. — Completed cone. Fig^. B.— Completed i)atteni for the silk net. 

 (Both after Apstein.) 



The net has the form of a truncated cone (Fig. A), whose 

 side {i — 40 cm.) and radii of the ends (A^ 12.5 cm., and 

 r = 2 cm.) are known. The silk exposed in the net has the 

 area and dimensions of the surface of this truncated cone. 



