294 NEW YORK STATE MUSEUM 
close relationship existing between S. excelsior and S. cestro- 
tus is also indicated by the presence of paired spinous appendages on 
the first pair of legs of the former which correspond to those on the second 
and third pairs of legs in S. 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 by, S. cestrotus, relates to the structure of 
the eyes. The carapace of Beecher’s restoration isa 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 
of S. cestrotus the eye presents an aspect very 
like that of this specimen of S. excelsior. Ina 
few better preserved examples however [pl. 49, fig. 1,] 
Figure 66 The terminal 
: ; : ; ; : portion of the median 
the eye is highly prominent, looking like a beanlying = f"""" nee ae Sty * 
on the carapace and the large semilunate visual sur-  lonurus excelsior, 
: showing the ocelli. Nat- 
face surrounds a small, subcircular top area [pl. 50, ural size. (FromHall & 
fig. 1]. The logical inference hence is that the visual i 
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 isthe outer end of the palpebral 
lobe and the entire surrounding concentric area the visual surface. The 
latter part of this inference is at once invalidated by the fact of the ex- 
tension of the surface sculpture upon the concentric area. The first part 
of the inference that the broken down inner circular areas were parts of the 
