126 MR. H. BOLTON ON A GIANT DRAGON-FLY [June 1914? 



coriaceous frontal marginal bar to the costa, the presence of spines 

 upon the frontal and hinder margins, and the occurrence of an 

 oblique commissure uniting the cubital and anal veins. 



Horizon. — Upper Coal Measures, Radstock (Somerset). 



Dimensions. — The dimensions of the wing-fragment have 

 already been stated, and a reconstruction of the whole insect — based 

 upon that of Meganeura monyi — gives the insect a total wing- 

 length of 7 § inches. 



Allowing a width of 1 inch for the diameter of the thorax, the 

 whole wing-span of Meganeura radstockensis would not have been 

 less than 16 inches. This is about 8 inches less than the wing-span 

 of M. monyi. 



I desire to express my indebtedness to Mr. J. W. Tutcher, for 

 the skill with which he has photographed the wing-fragment ; and 

 to Mr. R. E. J. Bush, for the drawing of the restored outline of 

 the wing. 



EXPLANATION OF PLATES XVIII AND XIX. 



Plate XVIII. 



Pig. 1. Photograph of the wing- fragment, showing the positions of the anterior 

 and posterior pieces, and the area formerly occupied by the radius 

 and media. Enlarged X 1'3. 



2. Proximal portion of costa and sub-costa, showing the tubercular anterior 



edge, and the backward slipping of the costa over the sub-costa. 

 Enlarged X 4. 



3. Distal portion of the costa and sub-costa, showing the spinous anterior 



border of the former, the cross-branches uniting the two veins, and 

 a median line of tubercular ornament upon the sub-costa. Enlarged 

 X 4. 



Plate XIX. 



Pig. 1. Proximal portion of the inner margin, showing the development of 

 stout submarginal spines. Enlarged X 4. 



2. More distal portion of the inner margin, showing the submarginal 



spines. Enlarged X 4. 



3. Restoration of the wing of Meganeura radstockensis, upon the lines 



of M. monyi. Half of the natural size. 



Discussion. 



The President (Dr. A. Stkahan) complimented the Author on a 

 most interesting and detailed piece of work, and commented on the 

 extreme beauty of the photographs by which the communication 

 was illustrated. 



Mr. G. W. Young congratulated the Author on a very delicate 

 and successful investigation, and regretted that such papers were 

 not more frequently presented to the Society. It seemed to him 

 almost incredible that objects of such extreme tenuity as dragon- 

 flies' wings could ever be preserved so perfectly as the specimen 

 shown. He doubted that the spines of the fore edge of the hind- 



