Mr. S. H. Scudder on Mesozoic Cockroaches. 61 



Scutinohlattina recta^ sp. nov. 



This species, the smallest and most abundant of all in the 

 Triassic rocks, is rather slenderer than the others, and has the 

 surface finely reticulated. The mediastino-scapular and 

 externomedian veins run side by side in perfectly straight 

 lines from the middle of the base to the middle of the tip, the 

 branches, very few in number, parting similarly on the two 

 sides. The costal is more arched than the inner margin, and 

 where they can be made out the one or two anal veins seem 

 to run to the margin; but all the veins on the wing are 

 exceedingly obscure. Length of wing 6-3 millim. ; breadth 

 2'4 millim. 



Triassic beds near Fairplay, Colorado. 



III. On the Genera hitherto proposed for Mesozoic Blattarice . 



Brodie, in 1845, published figures of a considerable number 

 of Mesozoic cockroaches, but named only one, which he 

 referred to the genus Blatta. In 1852 Heer figured and 

 named another under the equally broad generic name Blat- 

 tina. Westwood, in publishing in 1854 a considerable 

 addition to our knowledge of the cockroaches of the English 

 Mesozoic rocks, separated four somewhat peculiar forms under 

 the generic term Blattidium ; the rest were unnamed. Giebel, 

 two years later, named a considerable proportion of Brodie's 

 and Westwood's species ; while placing a considerable num- 

 ber under Blatta and Blattina^ he divided the rest under three 

 new genera — Rithma^ Elisama, and Nethanta — the last in- 

 cluding the only one of Westwood's species of Blattidium 

 which was noticed. On the other hand, Heer, in 1864, 

 divided all the Mesozoic species between Blattina and Blat- 

 tidium^ placing in the latter all of Westwood's species, 

 together with all those referred to new genera by Giebel. 

 Finally, a few years ago, E. Geinitz proposed for a Triassic 

 species described by him, and one previously published by 

 Heer, the new generic term MesoUattina. 



There is no question that the forms described by West- 

 wood, after eliminating the one separated by Giebel under 

 the name of Nethania^ form a very distinct group ; but none 

 of the species since added to it belong here, so that 



Blattidium 



should stand much as first limited (though not described) by 

 Westwood. Probably, however, it should be still further 

 restricted by the elimination of B. achelous, Westwood. The 



