THE EURYPTERIDA OF NEW YORK 165 
described by Holm [text fig. 32] has not been seen in our material, 
probably because, as in Limulus, only the mature individuals after the last 
molt possessed it. Besides the long paired spines, each segment was fur- 
nished with one or more short, blunt spines [pl. 7, fig. 2], located at the 
anterior margin. The clawlike terminal segment and the spines of the 
penultimate segments are shorter than the others. As in most Eurypteri, 
the fourth endognathite lacks the spines, except those of the last two 
segments, and is relatively longer and more slender. As none of the coxal 
segments of the first three pairs of endognathites have been found detached, 
we are unable to describe them beyond stating that they are 
short and broad and bear at the inner upperangles, dentate manducatory 
faces with short conical teeth. They apparently show the progressive changes 
in form posteriorly as described by Holm. The coxa of the fourth endog- 
nathite is seen on plate 7, figure 6. Its length and width are nearly 
equal, while in the preceding coxae the width surpasses the length. The 
manducatory edge is borne on a marked prolongation. The circular foramen 
' of the posterior margin, to which an auditory function has been ascribed, 
is well shown. Plate 4, figure 2, shows the mode in which the coxae of the 
endognathites are arranged like the tiles of a roof, exposing in ventral view 
only the upper margin and the prolongation bearing the manducatory edges, 
while plate 4, figures 2, 3, show the relative length and thickness of the 
endognathites. 
The swimming legs are strongly developed in this type. When reflexed, 
they reached to the sixth tergite, and are correspondingly stout. The 
coxa is usually well exposed [pl. 6, fig. 8; pl! 7, fig. 7, 8].' It is subquadrate, 
broader in front than behind ; the manducatory face is about one third the 
length of the inner margin and borne on a well defined neck. The face con- 
sists of a beveled chisel-like upper half followed by a more prominent row of six 
to seven denticles that are shorter than those of the other legs [pl. 7, 
fig. 6]. The second and third joints are short and ringlike. The stem- 
like process by which the second joint articulates with the coxa 
is distinctly seen in plate 7, figures 7, 8. The fourth segment is about one 
