. The Eurypterida of New York. Eurypterida; Paleontology. 2 94 NEW YORK STATE MUSEUM close relationship existing between S. excelsior and S . c e s t r o - t u s is also indicated by the presence of paired spinous appendages on the first pair of legs of the former which corres])ond to those on the second and third pairs of legs inS. cestrotus. We have above proposed the subgenus Ctenopterus for this well defined group of species. Another alteration of the restoration of S . excelsior, suggested by evidence afforded byS. cestrotus, relates to the structure of the eyes. The carapace of Beecher's
. The Eurypterida of New York. Eurypterida; Paleontology. 2 94 NEW YORK STATE MUSEUM close relationship existing between S. excelsior and S . c e s t r o - t u s is also indicated by the presence of paired spinous appendages on the first pair of legs of the former which corres])ond to those on the second and third pairs of legs inS. cestrotus. We have above proposed the subgenus Ctenopterus for this well defined group of species. Another alteration of the restoration of S . excelsior, suggested by evidence afforded byS. cestrotus, relates to the structure of the eyes. The carapace of Beecher's restoration is a cast from the Rutgers College specimen. In this the eye regions exhibit an inner circular depression described by Hall and Clarke as the eye. This is encircled on its outer edge by a conspicuous subsemicircular orbital ridge, but separated from the latter by a concentric level area bearing the same sculpture as the rest of the carapace. In much compressed or collapsed carapaces ofS. cestrotus the eye presents an aspect very like that of this specimen of S. excelsior. In a few better preserved examples however [pi. 49, fig. i,] ].-,„^,r^ 66 The umiinai the eye is highly prominent, looking like a bean lying on the carapace and the large semilunate visual sur- face surrounds a small, subcircular top area [pi. 50, fig. 1]. The logical inference hence is that the visual node of S. excelsior bulged in the same way and we have repre- sented it thus in our restoration. The intense concentric wrinkling of the area within the orbital ridge in the specimen in the National Museum is direct evidence of the collapse of the visual node. By analogy it would be necessary to infer that the central circular broken area in the eye of S . excelsior is the outer end of the palpebral lobe and the entire surrounding concentric area the visual surface. The latter part of this inference is at once invahdated by the fact of the ex- tension of the surface sculpture upon the concentric
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