THE OLDEST AIR-BREATHERS. 



399 



found abound in Eurypterids, or fossils of a crustacean allied to the 

 king-crab. 



Of the recent discovery of earlier Silurian insects, we have the fol- 

 lowing account given by M. Charles Brongniai't to the French Acad- 

 emy of Sciences : 



" Fossil insects have been found 

 in the carboniferous strata. The 

 coal-beds of Commentry have 

 furnished some thirteen hundred 

 specimens, and Mr. Scudder has |H 

 described six specimens that were 

 found in the Devonian beds of 

 New Brunswick ; but, until very 

 recently, no representative of that 

 class had been detected in any of 

 the more ancient formations. M. 

 Douville, a professor in the School 

 of Mines, has shown me a piece of 

 Middle Silurian sandstone from 

 Jurques, Calvados, bearing a dis- 

 tinct impression of an insect's 

 wing (Fig. 3). The state of pres- 

 ervation is not perfect, but we can 

 still distinguish most of the ner- 

 vation. The wing, which is about 

 thirty-five millimetres long, be- 

 longed to a blattid, an insect of 

 the cockroach family. The hu- 

 meral field is broad, and upon it 

 may be seen the superior humeral vein ; the inferior humeral vein, bifur- 

 cated at its extremity ; the vitrean or median vein, likewise divided into 



Fig. 3. Fossil Scorpion, from the upper Silurian 

 rocks of Lesmahagow, Lanarkshire, Scotland, 

 found by Dr. Hunter, Carluke. (Magnified two 

 diameters.) 



Fig. 3. Wing of a Fossil Blatta (Palceo- 

 blattlna Dovmllei). in a piece of Silurian 

 sandstone (natural size). 



Fig. 4.- 



-Restoration or the Fossil 

 Wing. 



two branches ; the upper and lower discoidal veins, with their very 

 oblique divisions meeting again at the end, just as they may still be 



