466 SAMUEL H. SCUDDER ON THE 



POROBLATTIXA Sciidcler. 



PoroUattina Sciidd., Proc. Acad. Nat. Sc. Philad., 1885, 38-39. 



Allied to Petrablattina, and especially the species of that genus found in the same Tri- 

 assic rocks, differing from them principally in the insignificant part played by the me- 

 diastinal area and the corresponding importance of the scapular area. The mediastinal 

 vein extends no furthei" out than the anal, tei-minating far I^efore the middle of the Aving, 

 and has consequently but a few offshoots; while the mediastinal, sweeping downward, 

 away from the costal margin at the termination of the mediastinal, occupies nearly half 

 of the wing before curving ujiward again to terminate above the apex. The externomc- 

 dian vein is arcuate and terminates on the lower margin not far from the tip, and has 

 only three or four superior longitudinal branches. The anal furrow is stronglj' arcuate. 

 The anal veins are nearly parallel to the inner margin, bat impinge upon it near the anal 

 furrow. 



This genus is peculiar to Fairplay and two species are known. 



TABLE OF THE SPECIES OF POKOBLATTINA. 



Scapular vein stvonjily sinuous, tlie proximal scries of branches simple IP. areuata. 



Scapular veiu geutly sinuous, the proximal series of branches deeply forked 2. P. lakesii. 



1. Poroblattina areuata. 



PL 41, fig. 5. 

 Porol)lattina areuata Scudd., Pi-oc. Acad. Nat. Se. Philad., 1885, 39. 



The costal border is considerably convex. The scapular vein is uniisually arcuate and 

 has a large number of mostly simple oblique branches. The externo- and internomedian 

 veins, on the contrary, have few and distant branches, and the former is also strongly ar- 

 cuate. The whole surface of the wing is broken by closely crowded cross-veins, which are 

 more transverse to the whole wing than to the interspaces. 



Length of fragment, 5.5 mm.; probable length of wing, 10 mm.; breadth, 4 mm. 



A single rather imperfect specimen was obtained, No. 47, indicating a wing well 

 rounded and much shorter in proportion to its breadth than in the next species. 



2. Poroblattina lakesii 



ri. 41, fig. 11. 

 Poroblattina laTcesii Scudd., Proc. Acad. Nat. Sc. Philad., 1885, 39, 



The costal border is nearly straight and the wing elongate. The scapular vein is much 

 less arcuate than in the preceding species and has a comparatively small numljer of dis- 

 tant, singly or doubly forked, oblique branches. The much less oblique branches of the 

 internomedian vein are more frequent but appear less croAvded from their simi)licity, 

 while those of the externomedian are more distant than the latter, and equally simple. 

 There is no sign of any cross-venation. 



Two specimens, Nos. 30, 73 and 74. This species like the preceding, is small, the 

 wing measuring about 12 mm. long, and 4.5 mm. broad. Named after Prof. Arthur Lakes 

 of the School of Mines at Golden, Colorado, the first discoverer of these fossils. 



