6 Bolton, "Mark S/imip" Collection of Fossil Insects. 



margin at all. The characters of the radial sector, median 

 and cubitus are radically different from those of P. Westzvoodi. 



I am of opinion that the ncuro])tcroid evidences of struc- 

 ture are more evident than any which may be considered proto- 

 orlhopteroid, and therefore assign it to a new genus of the 

 family Pcrlida\ under the name of ''''Mega gnat hc7 odonatiformis. 



\ Dr. A. D. Imms, who has kindly read my jiaper whilst 

 in manuscript form, has suggested that the specnnen may pos- 

 sibly come nearer to the SialidiC than to the Perlid<c; noting 

 that whilst the possession of great mandibles is a unique feature 

 amongst living and fossil Perlida?, they are, nevertheless, a 

 prominent feature amongst certain Sialidu\ This is certainly 

 the case, but I have attached more importance to the apparent 

 wing structure, and to the extremely long thorax than to the 

 size of the mandibles, the detailed structure of which it is im- 

 possible to make out. My own studies have led me to regard 

 the families of the Sialidcc and Perlidw as somewhat closely 

 allied in origin. Had the venation of the wings been more 

 complete, something more could probably have bcx^n said upon 

 the question of relationships.] 



Genotype. — ^lanchester ^luseum ; Register No., L5,56o. 



Horizon. — Stephanian. 



Locality. — -Commentry (Allier), Central France. 

 Mark Stirrup Collection. 



Sycoptero}i synijnetrica, gen. et. sp.n. PI. II.; figs, i and 2. 

 Deri\ation: Sycopteron, a-cvos = a fi.g; 7rre/7oi'= a wing. 



Generic diagjiosis. — Small insects in which the head is 

 large, rounded, and convex dorsally; wings fig-like in outline; 

 principal veins well developed, with few branches. 



Specific diagnosis.- — Wings g-io mm., costal margin almost 

 straight, sub-costa reaching the inner side of the wing apex. 

 Radius a powerful vein, to which the median and cubitus are 

 attached at the base. Median and cubitus veins simple. 



Amongst the insects in the Stirru]:) Collection is one of 

 special interest. It is a small insect, showing the head, thorax, 

 and the first pair of wings. In all probability it is whole, with 

 the hind wings concealed under the first pair, and the legs and 

 body below. Its total length is 1 1 mm. from the front of the 

 head to the end of the wings, and its greatest diameter (at the 

 free end of the wings) is not more than 5 mm. Its extreme 

 smallness makes its difficult to determine many details of struc- 

 ture, yet the princijial veins are clearly marked. The front of 

 the head is rounded and the sides almost straight. The upper 

 surface is convex, the convexity gradually diminishing to the 

 front margin, and ]>assing down into two flattened postero- 



*This generic name has been substituted for that of " Pseudoperhi."" 

 Avliich I first used. 



