. The Eurypterida of New York. Eurypterida; Paleontology. THE EURYPTERIDA OF NEW YORK 33 plate, termed the endocranium, plastron or entosternon,' which in its turn forms the fulcrum for other important muscles. Owen has shown that the glabellar furrows, or rather the entapophyses or infoldings to which the furrows correspond, are the bases of the powerful levators of the preab- domen and also of the muscles which serve to steady the entosternon while the latter furnishes the fixed points for the flexors or depressors of the preabdomen and the important muscles that hold and move the coxal join
. The Eurypterida of New York. Eurypterida; Paleontology. THE EURYPTERIDA OF NEW YORK 33 plate, termed the endocranium, plastron or entosternon,' which in its turn forms the fulcrum for other important muscles. Owen has shown that the glabellar furrows, or rather the entapophyses or infoldings to which the furrows correspond, are the bases of the powerful levators of the preab- domen and also of the muscles which serve to steady the entosternon while the latter furnishes the fixed points for the flexors or depressors of the preabdomen and the important muscles that hold and move the coxal joints of the Figure 6 Longitudinal section of Limulus liv, liver; pr^ proventriculus; st, stomach; h!, heart; cp, cartilaginous plate, entosternon; inty intes- tine; a, anus; br, brain. (From Packard) The glabellar furrows of Eur5rpterus thus correspond quite precisely •in position and extension to those of Limulus and the appendages on the ventral side are entirely homologous and of like position and struc- ture; hence it is to be inferred that the same system of muscles existed in Eurypterus as in Limulus, that also Eur3^pterus may have possessed a cartilaginous entosternon and that the glabellar furrows served as bases for the levators of the preabdomen and the lateral levators of the ento- sternon. These furrows are also well developed in species of Stylonurus, ' *The importance of this internal skeleton to the muscular system of Limulus is fully described by Owen [Palaeontographical Society 1878. 32: 187].. 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 the original Clarke, John Mason, 1857-1925; Ruedemann, Rudolf, 1864-1956. Albany, New York State Education Department
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