378 NEW YORK STATE MUSEUM 
The specimen figure 3 has suffered strong compression in anteroposterior 
direction and is therefore not competent to indicate the form of the 
carapace in this stage, but it corroborates the evidence from the other 
as to the relatively increased size of the compound eyes and the distinct- 
ness and position of the ocelli. 
The carapace has lost its position as the broadest part of the body. the 
preabdomen having been completed and become the widest portion. In 
other growth-stages of eurypterids obtained at Otisville, the postabdomen 
is completed before the preabdomen, and it is hence to be inferred that 
in the specimen figure 3 the number of segments is complete. This 
is also suggested by the presence of a narrower first preabdominal tergite 
such as is found in the mature stage. | 
The compound eyes are relatively larger than in the nepionic stage, 
occupying fully one half the sides of the carapace, but less prominent. 
The compound eyes of the first specimen are especially notable for the 
distinctness with which a thickened ring is seen to surround the inner 
side of the eye. The same is already visible on the second nepionic speci- 
men hgure 2 and partially noticeable on the type. It probably surrounded the 
whole eye and its function was apparently to support the prominent cornea, 
corresponding in that to the orbital ridge in Stylonurus excelsior. 
Measurements. 
Type, carapace, length, 12.3 mm; width, 15.5 mm 
Length of first tergite, 1.5 mm 
Width of largest tergite observed [pl. 82, fig. 8], 25.5 mm 
Length of same, 9.9 mm 
Largest telson observed [pl. 82, fig. 11], length (incomplete), 35 mm; 
width (restored), 60.2 mm 
smaller telson, width, 7.4 mm; length, 7.7 mm 
smallest specimen, length (incomplete), 1.6 mm; width, .8 mm 
Horizon and locality. Rare in the Shawangunk grit at Otisville, N. Y. 
