. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Raymond : Fauna of Upper Devonian of Montana. 151 venter. Some of these ribs point slightly forward, others a little backward. The ribs become gradually further apart on each whorl, until on the body whorl they are quite distant from each other. They do not bear any fixed relation to the cameras, for, as may be seen on the figures, a rib may be between the septa, or may be cut in any direction by a septum. The dorsum is slightly concave and is frequently marked by a revolving line showing the
. Annals of the Carnegie Museum. Carnegie Museum; Carnegie Museum of Natural History; Natural history. Raymond : Fauna of Upper Devonian of Montana. 151 venter. Some of these ribs point slightly forward, others a little backward. The ribs become gradually further apart on each whorl, until on the body whorl they are quite distant from each other. They do not bear any fixed relation to the cameras, for, as may be seen on the figures, a rib may be between the septa, or may be cut in any direction by a septum. The dorsum is slightly concave and is frequently marked by a revolving line showing the position of the siphuncle. As shown by the figures, the suture is very simple. This species is more closely related to Platyclymenia anmilata (Munster) than to any other described species, and differs from it principally in the more depressed section of the whorls and the coarser ribs. A copy of Freeh's figure of Platyclymenia annulata from his monograph ^^Uber devonische Ammoneen ; Beitrdge zur Palli- ontologie und Geologie Osterreich-Ungarns und des Orients,'''' Band XIV, Heft I und 2, 1902, t. 2, figs. 6<r-6r, is here introduced for comparison (Plate VII, figure 8). Locality. —This species is found in the red shale, the green shale, arid the limestone of the Upper Devonian at Three Forks, Montana. Platyclymenia polypleura sp. nov. (Plate VII, FIGURES 4-6.) Description. —This species may be described by saying that it dif- fers from the preceding in its somewhat smaller size, shallower cam- eras, and, principally, in the much more numerous and finer ribs which ornament the surface. The ribs of the body whorl, instead of becoming very strong and distant, become weaker and more numerous, and extend further on the venter. This species bears much the same relation to Platyclymenia ameiHcana that the variety Platycly- ^ „, menia annulata densicosta Freeh does to Platycly me- dymenia polypUu- nia anmdata (Munster). In surface ornamentation ;-<? Raymond, our species is
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