. Bulletin - United States National Museum. Science. '?!j^.Jr2*' Fig. 112.—Leptotrypa hexagonaus. a, the original type of the species, natural size, inckusting A Htolithes; &, surface of the same, X12. Middle Ordovician (Platteville) limestone, Min- eral Point, Wisconsin. (After Ulrich.) c, a fragment of limestone "with a Htolithes in- crusted BY this delicate betozoan. Kuckees shale (C2), Baron Toll's estate, Esthonia. apertures of almost twice the usual size are arranged in diagonally intersecting rows; these clusters are about 3 mm. apart, measm'ing from center to center. Zooecia r
. Bulletin - United States National Museum. Science. '?!j^.Jr2*' Fig. 112.—Leptotrypa hexagonaus. a, the original type of the species, natural size, inckusting A Htolithes; &, surface of the same, X12. Middle Ordovician (Platteville) limestone, Min- eral Point, Wisconsin. (After Ulrich.) c, a fragment of limestone "with a Htolithes in- crusted BY this delicate betozoan. Kuckees shale (C2), Baron Toll's estate, Esthonia. apertures of almost twice the usual size are arranged in diagonally intersecting rows; these clusters are about 3 mm. apart, measm'ing from center to center. Zooecia regu- larly hexagonal in shape, sometimes a little elongated, seven, measuring longitudinally, almost nine, diagonally, in 2 mm.; diameter of the smaller of the larger mm. Acanthopores prominent on the surface when well preserved. The usual occurrence of this species in America is as a delicate, lace-like expansion upon shells of the pteropod EyolitJies laconi Whit- field. The occurrence in the Kuckers shale is identical, even to a great resemblance of the incrusted pteropod to E. haconi, although this shell is probably the form described by Eichwald as Hyolithes striatus. The internal structure of Leptotrypa Tiexagonalis has never been figured and I am taking this opportunity of presenting thin sec- tions of the type, mainly for comparison with similar sections of the Russian form. Comparison of figures 113 and 114 will show prac- tical identity of structure in the corresponding parts of the sections. The size, shape, and thinness of the cells are especially similar. The Russian specimens, however, exhibit an interesting feature which has not been observed in the American examples. This is the occur- rence exclusively of small, thick-walled, closely tabulated mesopore-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble
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