BOLTONITES RADSTOCKENSIS. 141 



(? aborted spiracles) in anal area. Length of wing when complete about 190 mm. 

 or seven and a half inches. 



Type. — Proximal third of wing, in dark shale with plant-remains ; Sedgwick 

 Museum, Cambridge. 



Horizon and Locality. — Upper Coal Measures; Tyning Colliery, Radstock, 

 Somersetshire. Precise horizon uncertain. 



Description. — The fragment consists of the proximal portion only of a wing, 

 64 mm. long and 40 mm. in greatest width, and appears to have formed about 

 one-third of the whole. The wing has also been broken along the middle, and a 

 portion lost, due apparently to the shale breaking irregularly, and leaving an 

 uneven surface. The outer and inner parts of the wing-fragment still retain their 

 normal position relatively to each other, but a portion of the inner part of the 

 base is missing. 



The outer part of the specimen consists of two veins, the costa and sub-costa. 

 The inner portion shows the cubital and anal veins. The veins missing are there- 

 fore the radius and median. 



**>. 



Fig. 44. — Boltonites radstockensis (Bolton) ; restoration of right wing, based on that of Meganeura 

 monyi, Brongt., one-half natural size. Upper Coal Measures (precise horizon uncertain) j Tyning 

 Colliery, Radstock, Somerset. Sedgwick Museum, Cambridge. 



The outer wing-margin consists, not of a free alar expansion, as is usual in the 

 Protodonata, but of a coriaceous and tuberculated mass, which is well marked off 

 from the costa along its whole length. This thickened mass apparently represents 

 the free alar development seen in other members of the group. 



That other veins existed in the middle area of the wing is proved by the 

 remains of three short portions of a vein, lying in the middle of the interspace. 

 Not until these fragmentary vein-structures had been perceived, and the type of 

 Meganeura monyi studied in the Museum at the Jardin des Plantes, Paris, could its 

 relationship with the Protodonata be confirmed. The direct comparison of the 

 two wings also showed that the Radstock specimen had the same parallelism of 

 the principal veins, the co-existence of similar cross-veins, and the same distinctive 

 character of the anal area as M. monyi. 



The basal portion of the outer margin of the Radstock wing is swollen into an 

 elongated mass, which thins out distally, and probably did not extend beyond the 

 proximal third of the wing. It can be traced for a length of 20 mm., and near 

 the articulation is covered with numerous low, smooth-topped tubercles, arranged 



