MESOZOIC COCKROACHES. 451 



only in the character of the wing. The species is certainly distinct from any known on 

 account of its size alone, and the direction of the mediastino-scapular vein is such as to 

 lead one to presume it terminated at the very tip of the wing, which is of an oval shape 

 and rather broad for its length, tapering in the apical half to a rounded tip equally slop- 

 ing on both sides. The anal furrow is not very strongly arcuate, but unusually trans- 

 verse and the anal veins impinge on the margin. An upper surface is shown which is 

 slightly domed. Length, 4 nun.; breadth, 1.9 mm. 



The other object is a pronotum of a cockroach, 3.25 nun. broad and 2.3 mm. long, 

 broadly and transversely oval, the hinder margin less rounded than the front margin, 

 the disc slightly convex, with slight irregularities like gentle longitudinal plications, as 

 seen in the figure (fig. 2), the delicate edge very slightly marked by a darker line. 

 As it corresponds exactly to what we should expect of a pronotum belonging with the 

 wing on the same stone, and is only about 2 cm. removed from it, and as no other known 

 mesozoic species approaches it closely in size, there can be little doubt that they belong 

 together. The specimens come from the middle Purbecks of Dorset, England. 



The other ohjects found on this same stone are also figured on the same plate. One 

 of them, Pterinoblattinapluma, is described elsewhere in this paper. Fig. 4 (8b) is fig. 

 14J of Westwood and considered by him as the wing of a grasshopper. Fig. 10 (8/") is 

 fig. 14-' of West wood and considered by hhn as one of the Trichoptera. Fig. 12 ( 8rZ) 

 is fig. 14* of "Westwood, also considered by him as trichopterous. Fig. 13 (Se) is fig. 

 14*. of Westwood and named by him Cercojndium Telespliorus. These will be dis- 

 cussed at some future time, and are only mentioned here to explain the plate, accord- 

 ing to AYestwoodVs views. 



MESOBL ATTIXA E.Geinitz. 



Mesoblattlna E. Gein., Zeitschr. deutsch. geol. Gesellsch., 1880, 519-520; Scudd., 



Proc. Acad. Nat. Sc. Philad., 1885, 114. 



This genus, proposed at first by Geinitz as a sub-genus for a couple of species of mes- 

 ozoic cockroaches, on account of the course of the anal ncrvures, was afterwards ex- 

 tended by him to include another species, which disagreed in this particular from the 

 others. In this he was right, inasmuch as the group, which should be accorded generic 

 value, contains forms which vary considerably in this respect. The characters referred 

 to in my paper on mesozoic cockroaches (see above) relating to the course of the inter- 

 liomedian and externoiuedian nervules seem to be more important. The genus was the 

 most prolific of any in mesozoic times. The wings are generally slender and parallel 

 sided or nearly so, though in not a i'vw they taper as conspicuously as in most of the 

 species of Rithma, and one species at least is broadly oval. The flat humeral field is 

 nearly always large and conspicuous, and the costal area large as in Rithma, from which 

 it is distinguished mainly by its greatest peculiarity, which is the basal sinuosity and 

 subsequent almost completely longitudinal course of the externomedian and interno- 

 median veins and all their branches, the latter even rarely touching the border before 

 the apical half, and generally not before the apical fourth or fifth of the wing, while the 

 anal furrow does not extend out after them, but meets the border at a broad angle. In 

 addition to this, the veins of the anal area show in a considerable number of species (in 



