The Quarterly journal of the Geological Society of London . rontal tubercularbar not as a modified alar area,but as a highly-modified costa,closely attached to the sub-costaalong its whole length. If sucha view be taken, the secondprincipal vein would be theadius, and the media and theein-complex developed from itould alone be a view I had once taken,but have abandoned in favourof that already set forth. Con-sidered as a Meganeurid wing,the Radstock specimen is noprimitive structure, but a highly-modified wing, in which a se-condary development of spinesand tubercles is a strong fe
The Quarterly journal of the Geological Society of London . rontal tubercularbar not as a modified alar area,but as a highly-modified costa,closely attached to the sub-costaalong its whole length. If sucha view be taken, the secondprincipal vein would be theadius, and the media and theein-complex developed from itould alone be a view I had once taken,but have abandoned in favourof that already set forth. Con-sidered as a Meganeurid wing,the Radstock specimen is noprimitive structure, but a highly-modified wing, in which a se-condary development of spinesand tubercles is a strong fea-ture. In the absence of thehinder wing, it is not possibleto determine whether the mar-ginal spines upon the innerborder served for interlockingthe two wings during flight,but some such function appearsto be suggested by the if it should be consideredthat the difference which separ-ated the Radstock specimenfrom 3£eganeura monyi was ofgeneric rank, the fragmentarycharacter of the specimen, andmy consequent inability to de- o 2 8 ^ ^ I5 ^^. termine all possible genericcharacters, causes me to placethe specimen provisionally in the genus Meganeura, and as a new species—to which I attach the name of radstockensis. The specific characters are the presence of a tubercular and 126 MR. H. BOLTON ON A GIANT DRAGON-FLY [June 1914? coriaceous frontal marginal bar to the costa, the presence of spinesupon the frontal and hinder margins, and the occurrence of anoblique commissure uniting the cubital and anal veins. Horizon.—Upper Coal Measures, Radstock (Somerset). Dimensions.—The dimensions of the wing-fraginent havealready been stated, and a reconstruction of the whole insect—basedupon 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, thewhole wing-span of Meganeura radstockensis would not have beenless than 16 inches. This is about 8 inches less than the wing-spanof M. monyi. I
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