. The Eurypterida of New York. Eurypterida; Paleontology. THE EURYPTERIDA OF NEW YORK also short and thick. The surface of the carapace exhibits in front an unusual sculpture consisting of intricately mingled short, coarse, curved ridges of confluent tubercles. On the posterior part of the carapace the tubercles are mostly separated. The axial knots on the segments were solid bodies. All these features combined demonstrate that the integument of this subgenus was not merely chitinous as in the typical Eurypterus, but much strengthened by calcareous deposits which became most promi- nent in the
. The Eurypterida of New York. Eurypterida; Paleontology. THE EURYPTERIDA OF NEW YORK also short and thick. The surface of the carapace exhibits in front an unusual sculpture consisting of intricately mingled short, coarse, curved ridges of confluent tubercles. On the posterior part of the carapace the tubercles are mostly separated. The axial knots on the segments were solid bodies. All these features combined demonstrate that the integument of this subgenus was not merely chitinous as in the typical Eurypterus, but much strengthened by calcareous deposits which became most promi- nent in the sculpture of the carapace and in the knots of the tergites. This thickening of the carapace is entirely in accord with the char- acter of the Guelph fauna described by the authors from New York, where the fact of the peculiar thick- ening of the shells in all classes, notably the brachiopods and mol- lusks, has been emphasized and been ascribed to the strongly saline water and in part to the life of the organisms on wave-beaten coral reefs. Tylopterus bey lei seems to be an adaptation to the same peculiar conditions which are also indicated by the character of the matrix of the fossil, a porous, coarse-grained dolomite. It would suggest itself to compare this species with the Carbonic eurypterids described by Etheridge ( stevensoni, see text fig. 48) and Woodward (E. scabrosus)in which the integiunent has become greath' thickened Vjy deposition of globular calcite (" cal- culi "). ' We have in another place considered these features as ph}-lo- gerontic in the Carbonic subgenus Anthraconectes and as due to the waning vitality of the race. It is hardly to be assiimed that the characters of the Siluric T . b o y 1 e i are due to the same gerontic conditions and that the latter is an ancestor of the Carbonic Anthraconectes. It would. Figure 42 Tylopterus boylei (Whiteaves). Holotype refigured in natural size, and enlarge- ment of sculpture of carapace. Please note tha
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Keywords: ., bookcentury1900, bookdecad, booksubjectpaleontology, bookyear1912
