1848.] BRODIE ON A FOSSIL DRAGON-FLY. 33 



rhomboidal. The expansion of the fore-wings is about 2| inches, 

 while the hind-wings have the anal area very slightly developed, much 

 less so even than in our English and far less so than in many exotic 

 species. The expanse of each wing is 7;^ inches ; the breadth of the 

 upper wings ^^ inch, the breadth of the under wings ^^ inch. The 

 veins are most beautifully perfect, and are better displayed as the 

 specimen is lying in the matrix with its four wings expanded, like 

 those of the same family from Solenhofen, and must evidently have 

 died under circumstances highly favourable to its preservation. But 

 in order to understand the peculiarity of this fossil Libellula, it will 

 be necessary to enter into a little detail as to the general distribution 

 of the veining of the wings in the family to which it belongs ; a point 

 which has been hitherto almost entirely neglected. 



" Taking yEskna maculatissima (Latr.) {grandis, Donovan), one of 

 the largest and commonest species of Libelhdidcey as a good type, we 

 perceive the arrangement of the chief veins of the fore-wings 

 (fig. B) to be as follows : — 



*' 1 . A subcostal vein extending from the base, nearly parallel with 

 the fore-margin for half its length, where it joins the margin at an 

 angle. 



"2. A median vein (behind the subcostal) which extends from the 

 base to the tip of the wing, a small portion of the space between it 

 and the fore-margin being occupied, near the tip of the wing, with 

 the oblong black stigma. 



" 3. A submedian vein, extending from the base to the hind-margin 

 of the wing, about one- third of its length from the tip. 



" 4. A posterior vein which extends from the base to the hind-mar- 

 gin of the wing at about one-third of its length from the base. 



" Between the median and submedian veins, there is a short connect- 

 ing vein at about the distance of one-third of an inch from the base 

 of the wing, and from the middle of this connecting vein a long vein (*) 

 is emitted, the branches of which occupy all the space at the hinder 

 extremity of the wing between the median and submedian veins. 

 There is also emitted a short oblique vein (**) which soon again joins 

 the submedian vein ; the space between them forming a long narrow 

 (characteristic) triangle (t). 



" I will not here stop to inquire whether the veins emitted from this 

 short transverse connecting vein are to be considered as branches of 

 the median or of the submedian vein, but I believe them to be- 

 long to the former. At a distance of about half an inch from 

 the base of the wing, we see another characteristic triangle (f f) 

 (extending between the submedian and posterior veins), the apex of 

 this second triangle joining the apex of the former one, and pointing 

 to the tip of the wing. The short base of this triangle is formed by 

 an oblique vein (o) between the submedian and posterior veins. We 

 also see a vein {ooo) branching off from that angle of the second tri- 

 angle which is towards the hinder margin of the wing, and which ex- 

 tends almost parallel with the extremity of the posterior vein (oo). 

 The hind-wing differs in no respect from the fore-wing in the arrange- 



VOL. V. PART I. D 



