MESOZOIC COCKROACHES. IJ7 



Rithma Hasina. 

 PI. 46, fig. 7. 



[Without name] Brodie, Foss. Ins. Engl., 101, PI. 8, fig. 12. 

 Blattina Hasina Gieb., Ins. Yorw., 317. 



Blattidium liasinum Heer, Viertelj. naturf. Gresellsch. Zurich, ix, 289. 

 Rithma Hasina Scudd., Proc. Acad. Nat. Sc. Philad., 1885, 111. 



By the kindness of Rev. Mr. Brodie, I have had the opportunity of studying the orig- 

 inal specimen shown in PI. 8, fig. 12, of his work, and find that it differs so much from 

 the figure given that a new drawing is necessary, which shows better than the original 

 that it belongs in Rithma. The wing exhibits an under surface on a dirty light brown 

 stone, on which the veins show slightly darker; it is very slightly concave, the interspaces 

 being slightly depressed in general, and rather markedly depressed where figured in white. 

 The wing is largest just before the middle, tapers regularly beyond, and probably had a 

 well rounded tapering tip, but the apex is much broken. The costal margin is gently 

 arcuate and the inner margin straight. The humeral field is very large, broad and ex- 

 tends to the middle of the wing, is flat, and does not partake of the concavity of the rest. 

 The mediastino-scapular vein is rather strongly sinuous and terminates just above the tip 

 of the wing, the broadest part of the costal area being in the middle where it occupies 

 nearly half the wing. The veins of this area are tolerably numerous, longitudinally ob- 

 lique, parallel, the basal ones simple, the apical forked. The externomedian vein and 

 its branches are disposed almost exactly as in 7?. disjuncta, but occupy a little less space 

 on the margin, being more displaced by the internomedian veins, which from base api- 

 cally change their course conspicuously, the basal branches being almost transversely 

 oblique with a slight terminal curve outward, the outer arcuate at root and nearly longi- 

 tudinal beyond; the branches on the costal and inner margins have a similar distance 

 apart. The anal area is very large, the furrow being roundly bent in the middle and 

 transversely oblique beyond, but yet reaching nearly or quite half-way down the inner 

 margin and opposite the basal forking of the externomedian vein; it is not prominent, 

 and would appear to have been no more strongly depressed (on upper surface) than the 

 other veins. 



Length of fragment, 12 mm.; probable length of wing, 11.5 mm.; breadth of same, 

 5.25 mm. The specimen comes from the Lias of AVainlode, Strensham, England. 



Rithma formosa. 



Blattina formosa Heer, Lias-Ins. Aarg., 15, PL, figs. 11, 12; Id., Urw. Schweiz, 83, PI. 



7, figs. 1, lb. 

 Rithma formosa Scudd., Proc. Acad. Nat. Sc. Philad., 1885, 111. 



In this species, in which the typical rounded wedge-shaped form of the wing is excel- 

 lently shown, and only interfered with by the lateral expansion of the anal area, perhaps 

 due to displacement by the crushing of its vaulted form, the humeral field is very narrow 

 and small, the costal area broad, equal and appearing to embrace the tip (the figures are 



5IEMOIRS BOSTON BOC. NAT. HIST. Vor.. III. '2 



