152 



MR. H. BOLTON ON INSECT-REMAINS [Feb. I9II, 



of the Mynyddislwyn and Swansea 4-foot Seams as correct, it 

 follows that of the nine specimens obtained, six came from the 

 Mynyddislwyn horizon at the base of the Upper Series. Two speci- 

 mens have been obtained from shales associated with the Graigola 

 Seam, and a 22-inch seam 40 yards below it ; while one specimen 

 comes from shales near the Rhondda No. 2 Seam, and therefore on 

 the same horizon as the example of Etoblattina {Archimylacris) 

 woodwardi Bolton, already described by me. 1 



It thus appears that the whole of the insect-remains are refer- 

 able to three horizons, one at the base of the Upper Series, and 

 two in the upper part of the Pennant Series. The specimens, the 

 register-numbers of which in the books of the Geological Survey 

 are 24501, 24502, 24503, 24504, 24505, 24506, 24507, 24508, all 

 come from the Mynyddislwyn Vein ; 245U 1-24503 having been 

 obtained from the Gellideg level, and 24504-24508 from the 

 Gwernau level, both in Monmouthshire, near Maes-y-cwmmer. No. 

 24510 is from the 4-foot Seam of Swansea, and therefore, as supposed, 

 on the Mynyddislwyn Vein horizon. Nos. 24511 and 24512 are 

 from shales associated with the Graigola Seam, and a 22-inch seam 

 40 yards below it ; while 24509 is from the No. 2 Ehondda Seam. 



III. Description of the Specimens. 

 Archimylacris sp. indet. (PI. VII, fig. 2.) [Reg. No. 24508.] 



Impression of the basal portion of the left tegmen. A good 

 portion of the base is hidden ; the anal area is either concealed 

 under a large pronotal shield or is absent ; and two-thirds of the 

 distal part of the wing are also gone. This is all the more to be 

 regretted, because of the presence of a detached pronotum, which 

 will be described later. 



The sub-costal area is strap-shaped, the vein running parallel to 

 a very slightly curved outer wing-margin. The vein is thin, much 

 less robust than the adjacent radius, and gives off a single branch 

 low down, which passes obliquely forward, forking just before 

 reaching the margin. The main stem of the sub-costa also forks 

 at the same level, and sends two large branches to the distal end of 

 the sub-costal area. Only the main stem and its terminal forks 

 can be seen in the photograph. The radial vein, while stronger 

 than the sub-costal, is less so than the median vein, and its branches 

 are correspondingly feeble. Three branches, all directed outwards, 

 can be distinguished, and all follow the same oblique direction as 

 those of the sub-costa. Whether the radius reached the tip of the 

 wing, it is of course impossible to say, but the obliquity of the veins 

 renders this very likely. 



The media is small, and branches high up, near the middle of 

 the wing. Only faint traces of two branches are discernible near 



1 Geol. Mag. dec. v, vol. vii (1910) p. 147. 



