THE EURYPTERIDA OF NEW YORK 187 
This we have identified with the nepzonic stage since it can not be much 
older than embryonic. It is represented by the two specimens plate ar, 
figures I, 2. | | 
Herein the most striking differences from the ephebic stage are: 
1 The great width and small length of the body and the resulting 
rapid contraction from the preabdomen to the postabdomen. 
2 The excessive width and small length of the subtriangular carapace. 
3 The great size of the compound eyes. 
4 The shortness and great width of the segments. 
5 The relatively greater size of the swimming legs. 
In these nepionic specimens the width of the body is to its length 
as 3: 8, and in the ephebic stage as 3:15, hence the former stage is about twice 
as stout as the latter and conversely the contraction of the body is twice 
as rapid in the nepionic stage. 
The carapace of the mature Eurypterus maria is one third 
wider than long (3:2), while that of the youngest nepionic specimen is 
twice as wide as long (4 : 2) and in the other much larger nepionic specimen 
the proportion is still 34:2. The antelateral angles are so strongly trun- 
cated that the carapace approaches a triangular outline. 
_ In this nepionic stage the compound eyes may reach one half the 
length of the carapace [pl. 21, fig. 3], while in the ephebic form they occupy 
only one third that length. They also lie farther forward and converge 
strongly on their longitudinal axes, while in mature individuals they either 
converge slightly or are subparallel. This strong convergence in the 
nepionic stage is continued into the neanic stage [pl. 21, fig. 9] and is 
in harmony with the convergence of the lateral margins. It is further to 
be noted that the outline of the ocular node is broadly elliptical in this 
stage and that the crescentic visual surface is not to be distinguished from 
the ocular node. It is therefore possible that the visual surface extended 
over the whole node and not until later became restricted to the crescent 
band or anterior side of this node. The appearance of these nodes as 
represented in figures 9 and 3 would seem to support this view. In the 
