112 Miscellaneous. 



The CucTcronches of the Carboniferous Epoch. 

 By M. Charles Brongniart. 



In the neuration of the first pair of wings Mr. Scudder finds little 

 difference between the recent and fossil cockroaches. The latter he 

 divides into two families, the Blattiuariie and the Mylacridae, dis- 

 tinguished chiefly by the arrangement of the mediastinal nervure. 

 In the Blattinarise the branches of this nervure start at regular 

 intervals from a common trunk, so that the mediastinal ai'ea is 

 usually in the form of a band. In the Mylacridte the branches of 

 the mediastinal nervure originate from a common point at the base 

 of the wing and appear to be arranged in a radiate manner around 

 this point. 



Hitherto the Mylacrida? have been regarded as peculiar to the 

 United States, but the author states that they are as numerous aa 

 the Blattinaria; at Commentry, w^hero more than six hundred impres- 

 sions of them have been collected by M. Fayol. 



As authors have generally had only wings at their disposal they 

 have been unable to give any precise information as to the form of 

 the body. M. Brongniart now confirms Mr. Scudder's di\'ision of the 

 group into Blattinaria3 and Mylacridiie by characters drawn from the 

 body. The Blaltinarioe have a very rounded prothorax, narrower 

 than the part of the body covered by the wings ; the Mylacridae 

 have a thickset body with a wider prothorax, which, instead of 

 being rounded, is nearly in the form of a triangle with the base in 

 front. 



But these two families have a common character which distin- 

 guishes them from the recent Blattarioe. The last dorsal arch of 

 the abdomen in the fossils is widened, rounded, and divided into 

 three parts by two longitudinal grooves. In the males the last 

 ventral arch presents nothing extraordinary — it is truncated ; but 

 the females, instead of presenting, like the existing species, a keel- 

 like last ventral arch cleft longitudinally in the median line to facili- 

 tate the deposition of the ootheca, have this arch terminated by a 

 sort of slender borer, as long as the abdomen, widened a little and 

 keel-shaped at the base, but straight towards the extremity. This 

 apparatus resembles the ovipositor of Earycantha among the 

 Phasmidae rather than that of the Locustidae. 



The presence of this borer leads to the supposition that the Car- 

 boniferous Cockroaches, instead of leaving their eggs on the ground 

 enclosed in an ovigerous capsule, probably deposited them singly, 

 like the existing Phasmidae, perhaps introducing them, by means of 

 the borer, into the trunks of trees. — Comptes liendus, February 4, 

 1889, p. 252. 



