34 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 31, 



ment of the veins, but the space between the posterior vein and the 

 anal angle of the hind-wing is greatly enlarged. 



'* If the above description be compared with the veining of the Jbi'e- 

 wing (fig. c) in the equally common Libellula depressa, we find the 

 same general arrangement, as far as the subcostal, median and subme- 

 dian veins, and the branches between the two latter are concerned. We 

 also see the second characteristic triangle (ff ) behind the submedian 

 vein, with one of its angles united to the extreme angle of the first 

 elongated triangle (f ), but here the second triangle is shortened, and 

 its apex instead of pointing to the tip of the wing points to the hind- 

 margin ; arising from this apex we see the two curved veins {oo and 006) 

 which unite with the hind-margin of the wing about halfway between 

 the tip of the submedian vein and the base. In JEskna I have regarded 

 these two curved veins as the extremity of the posterior vein and a 

 branch of it ; but in Libellula depressa the posterior vein (p) is very 

 short, and extends only to the basal angle of the second triangle ; 

 whilst if we regard the two curved veins above alluded to as por- 

 tions of the same posterior vein, we might at first be led to believe 

 that the middle part of this vein had become obsolete ; whereas I be- 

 lieve we must from analogy look for it in some of the small veinlets 

 (composing hexagonal cells) between the base of the wing and the 

 transverse vein forming the side of the second triangle nearest to the 

 base of the wing. This is I think rendered quite evident b)'^ tracing 

 the veins of the hind-wings connected with these triangles in L. de- 

 pressa, where we see precisely the same general arrangement as in 

 JEsJma maculatissima. 



" Now the new fossil insect has an arrangement of the veins in con- 

 nection with these characteristic triangles quite different from either 

 of the arrangements above described, and which are found in the 

 whole oi oux LibellulidcB (as separated from the Agriones, &c.). The 

 subcostal and median veins are in their normal position, but in the 

 fore-wings (A*) the submedian is greatly deflexed, at about one-sixth 

 of an inch from the base, whereby the first elongated triangle (f ), 

 which I have above described as extending longitudinally from the 

 little transverse vein, between the median and submedian vein, along 

 the latter, is obliquely deflexed, so as almost exactly to represent the 

 second triangle in Libellula depressa. The posterior vein is also de- 

 flexed, whereby the smaller veins in connection therewith are thrown 

 so far out of their places that the second triangle (f f) takes an oblong- 

 quadrate form. The confusion is still greater in the hind- wings (A f ), 

 for here the first elongated triangle (f) occurs in its usual longitudinal 

 form ; but there is connected with it between its posterior apical half 

 and the deflexed part of the submedian vein, a regular, nearly equal- 

 sided triangle (f*), which, from being posteriorly bounded by the sub- 

 median vein, I consider only as analogically representing a portion of 

 the ordinarily narrow elongated first triangle ; whilst the second tri- 

 angle, which typically occurs between the submedian and posterior 

 veins, or is even sometimes apparent posterior to the posterior vein, 

 here becomes an oblique oblong-quadrate cell (ft) 5 between which and 



