Qg S. II. SCUDDER ON PALAEOZOIC COCKROACHES. 



branches of neighboring veins appears in this genus in the interspace between the externo- 

 median and internomedian veins. The combined internomedian and anal areas occupy, in 

 the species at the head of the series, somewhat more than half of the width of the wing at 

 the base, about one-half or slightly more than that in the others; and it generally dimin- 

 ishes gradually and regularly in width, and terminates, with rare exceptions, nearer the tip 

 than does the long mediastinal vein ; in some species the internomedian vein is nearly 

 straight; in others, however, while there is at first a rapid diminution in the breadth or 

 the area, the vein afterwards runs parallel to the inner border, and extends the area far 

 toward the tip of the wing; the vein has a large number of subparallel, straight or gently 

 curving branches, which are indifferently simple or branched, and the obliquity of which 

 corresponds in most cases very closely, although in a reverse sense, to the branches of 

 the mediastinal vein. The anal furrow is generally pronounced, and straight or gently 

 curved ; in one or two, however, it is very arcuate, and, while somewhat irregular in ter- 

 mination, its tip seems never to be far removed from the end of the basal third of the 

 wing ; the anal veins, where known, are frequent, parallel, arcuate, and generally simple in 

 the European species and in one of the American species ; but in the other American spe- 

 cies, G. fdscigera, they are very different, being nearly straight, multiple-forked, running 

 in a direction somewhat divergent from that of the anal furrow, and approaching the latter 

 only near its termination. 



The wings in this genus are slightly above the average in slenderness, being precisely 

 the same, as a whole, as in Etoblattina, the breadth being contained in the length scarcely 

 less than two and three-quarter times. 



This genus appears to be most nearly allied to Hermatoblattina, from which it differs 

 sufficiently in the superior position of the branches of the scapular vein ; from Etoblattina 

 and Archimylacris it may be separated at once by the great length of the mediastinal areaf 

 from Anthracoblattina it differs in having the branches of the externomedian vein superior 

 and not inferior ; Progonoblattina, with the wide extent and importance of its scapular 

 and externomedian areas, is readily distinguished from it-; Oryctoblattina for similar rea- 

 sons, as well as for many others, cannot be confounded with it; while the strong backward 

 curve of the externomedian vein in Petroblattina, with the extensive area covered by its 

 longitudinal branches, separates it from that genus at a glance. 



Most of the species of the genus, which next to Etoblattina is the richest in known 

 forms, come from the old world; but two American species must be placed here, although 

 the extensive development of the scapular vein would perhaps, as suggested above, warrant 

 separating them as a peculiar section. 



Gerablattina Goldenbergi. PI. 3, tig. 13. 



Blattina Goldenbergi Mahr, Neues Jahrb. f. Mineral., 1870, 282-84, fig. 1 ; — Gold., Faun. 



saraep. foss., ii, It). 



Fore wing. The apical third of the wing being lost, its precise form cannot be described, 

 but it was evidently long and narrow ; the costal margin is regularly and rather strongly 

 arcuate, with a very prominent humeral lobe, the inner margin straight, witli its basal 

 angle rather broadly rounded. The veins originate much below the middle of the base 

 and curve strongly upward over a considerable distance, so as soon to occupy the middle of 



