A. H. Sivinton — On Fossil Orihoptera. 341 



are placed mucli closer tlian in the field-cricket, and their free and 

 upper edges are somewhat longer. Their shape is a half-moon, and 

 they are severally fastened to the shrill vein by a kind of columnar 

 prop at their centre. They are not quite perpendicular, but placed 

 slightly obliquely ; and the friction takes place at their flat and 

 concave upper edges when the wing-covers are rubbed or fiddled 

 upon one another. These bridges are not of like dimensions, and at 

 the origin and termination of the slirill vein are very small and 

 poorly developed, and of little power in stridulation. In the central 

 part of the vein they are well developed. They amount to some- 

 thing like 143, and have the following dimensions : Breadth, 0-0028 

 in. ; height, 0-0005 in. ; breadth of the prop, -0011 in." 



The microscopic character of the file shown by the fossilized 

 elytron of G. Brongniarti may be thus generally given. 



The lov/er part is broken away, so that the portion remaining 

 in the anal field shows only ten large teeth, each -015 in. broad, of 

 triangular profile ; these run obliquely across it, and present their 

 vertices or edges to the fore-margin of the elytron. These teeth or 

 bridges are then attenuated from the point where they enter the 

 internomediate field ; more than twenty are observed to traverse 

 in a flattened curve, in a direction almost at a right angle to their 

 former course, to the vicinity of the scapular vein, where they 

 vanish : the whole adjustment presenting the curved line of a flat 

 parabola or ellipse, with semi-major and minor axes of -16 in. and 

 ■1 in. 



Thus, then, we see that this ancient instrument of music had 

 already attained, to all appearance, an efficiency at least thrice that of 

 our modern house-cricket, and must have emitted notes that rang 

 widely over the tropical forest that clothed our island in the old 

 days of the Coal period; and we may conjecture that each afternoon 

 and evening it enlivened the stilly watery surfaces with its dull and 

 incessant scraping.^ 



These plaintive love-notes, weird and wild, doubtless evoked a 

 thrill of kindred emotion in the bosoms of numberless Batrachia, 

 who found a home amid the swamps and morasses abounding in 

 those ancient Cryptogamic Forests, and who answered, by a chorus 

 of equal sweetness, the music of their Orthopterous companions. 



EXPLANATION OF PLATE XIV. 



Fig. 1. — Gryllacris (recent). Under surface of left elytron. Twice natural size. 

 1 and 2. The bifurcate scapular vein. 



3. Externomediate vein. 



4. Internomediate vein. 

 5 and 6. Anal vein. 



Fig. 2. — Gryllacris Ungeri, Heer (restored). From the Eocene Tertiary, Eadoboj, 

 Austrian Croatia. Natural size. Plant, Ruppia pannonica, linger. 



Pig. 3. — Gryllacris {Corydalis) Brongniarti, Audouin, sp. Under surface of left 

 elytron, showing what appears to be the file of an Orthopterous insect. 



Fig. 4. — File of the organ of stridulation of the common house-cricket, ti-om New- 

 port's figure in Tod's Anatomy. Much magnified. 



' Indeed it must have done so did its possessor at all aspire to the habits of two 

 great sections of our modern Saltatorial Orthoptera. 



