44 S. I. Smith on a Fossil Insect from Indiana. 



The result which I obtain is given, represented by my method, 



In fig. 32, I reproduce one of his more complex drawings, 

 viz : fig. 1 of his PI. II, lettering of course as before. The 

 visual result which he obtains bv viewing this figure with the 

 l)oint of sight at A is given in fig. 33, where A n is the combined 

 hues AR and A L of the drawing, bcde. The corresponding 

 lines of the cbawing, as seen by the right eve alone, and t' g' h' < 

 corresponding lines of the drawing as seen bv the left eve alone. 

 My result is given in fig. 34. By careful comparison of these 

 two results, remembering that capitals represent combined im- 

 ages, small italics right-eye images, and dashed italics left-eye 

 images, the nature of their differences will be readily under- 

 stood. Mr. Townes in his result makes the right eve shift to 

 the lefl o7ily the right portion, and the left shift to the 'right ml^j 

 the left portion, of the drawing. My result shows the w}iO^ 

 drawing shifted by the right eye to the left and the left eye to 

 the right. Mr. Townes has neglected entirely the left eye im- 

 ages of bcde, and the right eye images oi/g h i. Every one of 

 his visual results of figures drawn on the plane described, ex- 

 cept a few in which he used a median septum, are faulty in the 

 same way, and may be reconstructed on the same principle, with 

 the utmost certainty, even before performing the experiment. 



Oakland, Cal., Sept 27, 1870 



Art. IX — Brief Oontrihiiions to Zoology from the Museum oj 

 Yale College. No. JX.~Notice of a Fossil Insect from the Car- 

 boniferous formation of Indiana; by SIDNEY I. Smith. 



figu 

 Mus 



Paolia vetusta, gen. et sp. nov. 

 The fossil insect wing, represented in the accompanying 

 ^re, was sent for examination and description, from the 

 useum of Hanover CoUege, Indiana, by Prof E. Thompson 

 Nelson. It occurred in the " gi-it " quarry near Paoli, Orange 

 county, Indiana, and was discovered by the workmen while 

 sawing the stone into small pieces for whetstones. The fossil 

 is remarkably perfect, nearly the entire wing being beautifully 

 preserved, and of peculiar interest for showing the complete 

 wmg-skeleton of an insect so ancient as the coal period. It ^ 

 apparently the anterior wing of the left side, and measures 

 ii-54 m. m length and about -85 in. in breadth, the posterior 

 margin being slightly cut away by the saw. 

 ti,-'^^"^ *^® anterior border, the space between the second and 

 ttiird nervures is bent abruptly downward in the specimen, so 

 as to be somewhat foreshortened as seen in the figure. This 



