THE EURYPTERIDA OF NEW YORK 25 
Probably the majority of the remains found are the cast exuviae 
from the frequent moltings of growing individuals. The recent Limulus 
may take as long as eight years to reach maturity when, with the last 
molt, the clasping organs of the males appear. It is therefore probable 
that the eurypterids also were relatively slow in growth and it is a fair 
presumption that the great majority of the specimens found represent 
immature individuals. They are mostly dismembered and among the frag- 
ments of the integument, head shields with the first body segment attached 
are especially frequent. 
—__S—_— : 
Ss St SS = SO —= 10. wu. 2 
I. Qn. MW. Vv. Vv. v. e. 
Figure 3 Eurypterus fischeri Eichwald 
Diagrammatic longitudinal median section. a, carapace; b, metastoma; 1-6, tergites; 
I-V, sternites; 7-12, postabdominal segments. (From Schmidt) 
We consider it possible, or even probable, that the molting took place 
as in Limulus through a rent formed back of the frontal doublure of the 
head shield, through which the animal crawled out. Not only have 
specimens been found, as the type of plate 6, figure 1, where there is 
a gaping rent along the front edge of the head shield, but it is also incon- 
ceivable that the animal could otherwise have freedits legs so as to pull itself 
out of its old integument. 
The test was thicker on the head shield for that is always less wrinkled 
and has retained its form better, and it was on the whole, thicker on the 
dorsal than on the ventral side. The appendages were also clothed with 
thicker test and the basal segments which attended to the mastication 
of the food were furnished with an especially thick cover. The postoral 
plate was likewise thick and is always well preserved. 
Scales. The test or exoskeleton is characteristically ornamented by 
scale markings. On the head shield these consist of tubercles which are 
mostly simple thickenings of the test, but in some forms, as 
Eurypterus pustulosus, may grow out into large hollow wart- 
