. The Eurypterida of New York. Eurypterida; Paleontology. THE EURYPTERIDA OF NEW YORK 67 /^'fr*^ tergites, as shown by uncompressed specimens [pi. 20, fig. 8] and by the common observation that in compressed specimens the stemites pro- trude on both sides from under the tergites [pi. 4, fig. 4]. Although there are but five stemites including the operculum corresponding to the six tergites of the preabdomen the former are relatively so much longer that they overlap each other with fully half their length. The stemites, the operculum included, bore the branchiae. Woodward was the first to observ
. The Eurypterida of New York. Eurypterida; Paleontology. THE EURYPTERIDA OF NEW YORK 67 /^'fr*^ tergites, as shown by uncompressed specimens [pi. 20, fig. 8] and by the common observation that in compressed specimens the stemites pro- trude on both sides from under the tergites [pi. 4, fig. 4]. Although there are but five stemites including the operculum corresponding to the six tergites of the preabdomen the former are relatively so much longer that they overlap each other with fully half their length. The stemites, the operculum included, bore the branchiae. Woodward was the first to observe platelike appendages of the stemites in Pterygotus which he described as lam- ellae, and Laurie observed appendages of the stemites in Slimonia which he desig- nated as " branchial lam- ; Holm found organs in Eurypterus correspond- ing to those described by Laurie, but considers them only as " Kiemenplatten " instead of " Kiemenblat- tcr," or as oval spongy thickenings of the outside of the thin, soft membrane on the upper side of the stemite, which probably served as attachment places to the branchial lamellae. He has also observed detached bundles of two or three extremely thin superjacent leaves which he considers with doubt as possible branchial lamellae. The " Kiemen- platte " or " branchial plate " exhibits a very .characteristic structure consisting of one or two trunk veins running parallel to the longitudinal extension of the plate and from which smaller branches proceed [sec text fig. 22]. In our material we have frequently been able to see the impression of the " branchial plates " from the dorsal side, as in the fine specimen of Eusarcus [pi. 29]. Detached branchial plates have also been observed. Figure 22 Eurypterus fischeri Eichwald. Portion of one of the posterior stemites, showing anteriorly the very delicate membrane of the interior side torn off and pushed forward and exhibitin;^ the oval att
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Keywords: ., bookcentury1900, bookdecad, booksubjectpaleontology, bookyear1912
