Mr. S. H, Scudder on Mesozoic Cockroaches. 63 



by Giebel, and this is certainly to be referred to Mesohlattina, 

 Geinitz. B. ramijicata is quite too imperfect to be considered 

 until better specimens occur. It is probable that R. antiqua 

 should be separated from the others, and the same may be 

 true of B. Westwoodi. This leaves two species, B. purhec- 

 censis and R. Morrisij which agree well together, and repre- 

 sent a group which seems to have flourished in Mesozoic 

 times, as I have seen a number of species from the English 

 Lias belonging to it ; and Blattina formosa^ Heer, from 

 Scliambelen, and Blattina Hasina^ Gieb., figured by Brodie, 

 also belong here. These wings are rounded wedge-shaped, 

 with the amalgamated mediastinal and scapular area so large 

 as to occupy about half of the wing, the vein running in a 

 slightly sinuous course to, or even below, the tip. The anal 

 area is generally pretty large, convex, and filled with parallel 

 veins, which terminate on the margin. The space between 

 is divided about equally between the externomedian and 

 internomedian veins, which generally take a somewhat 

 sinuous course, and fork with tolerable abundance, filling the 

 space with graceful lines, spreading like (sinuous) rays of a 

 fan. The genus is closely related to Neorthrohlattina of the 

 American Trias, but differs from it in the much greater area 

 covered by the amalgamated mediastinal and scapular veins. 

 The following described species may be referred to it : — 



Rithma purbeccensts. 



Rithma lyurbeccensis, Gieb. Faun. d. Vorw. iii. p. 319. Figured by 

 Westw. Quart. Journ. Geol. Soc. Lond. x. pi. xviii. fig. 32. 



Lower Purbecks, Durdlestone Bay, England. 



Rithma Morrisi. 



Rithma Morrisi, Gieb. Faun. d. Vorw. iii. p. 319. Figured by Westw. 

 Quart. Journ. Geol. Soc. Lond. x. pi. xviii. fig. 34. 



Lower Purbecks, Durdlestone Bay, England. 



Bith7na Jhrmosa. 



Blattina forinosa, Heer, Lias Ins. Aarg. p. 15, pi. H. figs. 41, 42 ; id. 

 Urw. Schweiz. pi. vii. figs, 1, 1 6 



Lias, Schambelen, Switzerland. 



Bithma Hasina. 



Blattina Hasina, Gieb. Faun. d. Vorw. iii. p. 317. Figured by Brodie, 

 Foss, Ins. Engl. pi. viii. fig. 12. 



Lower Lias of Wainlode, Strensham, England. 



