. Maryland geological survey. umber of interesting features were made out. Below a magnificationof 100 diameters the outlines of the epidermal cells appear as rows ofsmall, narrow-walled, almost square rectangles, the irregularly scatteredstomata showing as cells of darker color. With a higher power (385 334 Systematic Paleontology diameters) the outlines are still substantially rectangular, but the wallsare seen to be not straight but irregularly waved or undulatory, as shownin the figure. This waving is less regular and less emphasized than insimilar figures given by Schenk for the genus Pte
. Maryland geological survey. umber of interesting features were made out. Below a magnificationof 100 diameters the outlines of the epidermal cells appear as rows ofsmall, narrow-walled, almost square rectangles, the irregularly scatteredstomata showing as cells of darker color. With a higher power (385 334 Systematic Paleontology diameters) the outlines are still substantially rectangular, but the wallsare seen to be not straight but irregularly waved or undulatory, as shownin the figure. This waving is less regular and less emphasized than insimilar figures given by Schenk for the genus Pterophyllum, and seemsto be more pronounced in the lateral and less marked in the transversewalls. The cells are small, about 7 microns (2/3 obj.) in diameter, andthe walls are thin. The stomata are numerous and without regulararrangement, but the guard cells are all oriented alike and parallel,presumably to the long axis of the pinnule. This feature also differsfrom their arrangement in Pteropliyllum, as shown by Schenk, where. Fig. 10.—Cuticle of Dioonites Buchlanus viewed from within, X 385. they are less numerous and without parallel orientation. The guardcells are two in number and stout in form. Their upper surface is justat or slightly below the surface of the cuticle, and they are quite deep,becoming nan-ower inward. These features will enable observers todistinguish Dioonites from fragments of similar appearance like those ofNageiopsis in cases where the cuticle is preserved. This fine plant is very abundant in the lower Potomac, along theJames Eiver in Virginia, the splendid specimens figured on pis. li andlii coming from Sailors Tavern. The remains from Maryland, whichhave been identified as this species, are extremely poor and questionable,those so identified with a query by Fontaine from the locality on theBewley estate being here omitted as undeterminable. Maryland Geological Survey 335 It is a widespread older Cretaceous type, first found in the BarremianWernsdor
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectpaleont, bookyear1901
