30 FOSSIL INSECTS OF THE BRITISH COAL MEASURES. 



Prof. T. D. A. Cockerell has pointed out to me that the family name was 

 originally wrongly written " Pteronidiae," and that the generic name was ante- 

 dated by Pteronidea, Rohwer, 1911. He thinks that the difference is sufficient to 

 justify retention, although it is only a single letter ('Proc. U.S. Nat. Mus.,' vol. xlix, 

 p. 469, 1915). Handlirsch ('Revision Palaozoischen Insekten,' 1919, p. 15) has 

 made the same correction, but seems unaware that Cockerell forestalled him. 



Genus PTERONIDIA, Bolton. 

 1912. Pteronidia, Bolton, Quart. Journ. Geol. Soc., vol. Ixviii, p. 313. 



Generic Characters. Wings three times as long as wide. Radial sector with 

 five simple, backwardly directed twigs. Median dividing lo\v down into two 

 principal branches, and ending on the inner margin in five twigs. Cubitus stout, 

 divided into two principal branches, the foremost with two twigs, and the hinder 

 ending in four. Interstitial neuration of thin oblique nervures. 



Pteronidia plicatula, Bolton. Plate I, fig. 8 ; Text-figure 2. 



1912. Pteronidia plicatula, Bolton, Quart. Journ. G-eol. Soc., vol. Ixviii, p. 313, pi. xxxii, figs. 1 3. 



Type. Incomplete wing and impression ; Moysey Collection, Museum of 

 Practical Geology, Jermyn Street (nos. 30,224 and 30,225). 



FIG. 2. Pteronidia plicatula, Bolton ; restoration of left wing, natural size. Middle Coal Measures 

 (below Top Hard Coal) ; Shipley Manor Claypit, Ilkeston, Derbyshire. Moysey Collection, Mus. 

 Pract. Geol. (nos. 30,224 and 30,225). 



Horizon and Locality. Middle Coal Measures (below the Top Hard Coal) ; 

 Shipley Manor Claypit, Ilkeston, Derbyshire. 



Specific Characters. Wings triangular in outline, with subacute tip, strongly 

 plicated. Radial sector dividing into five simple twigs. Median with two prin- 

 cipal branches and five marginal twigs. Cubitus wide-spaced; two principal 

 branches, the inner doubly forked. 



Description. This is a long delicate wing, of which the outer marginal portion 

 and the base are missing. It was probably about 7075 mm. long, with a basal 

 width of 20 mm., reduced to 8 mm. near the tip. 



The outer margin must have been flatly convex, while the inner margin is 



