THE EURYPTERIDA OF NEW YORK 277 
attachment scars as the eurypterids. Even in the mature Limulus, 
the extensors, or abductors, and the flexors, or adductors, of the gill- 
bearing ventral plates are still subdivided into many radiating fascicul1, 
and likewise the extensors and flexors of the tail spine arise from a large 
number of fascicul1.' 
The longitudinal zones or series. of scales are especially distinct in . 
Eurypterus remipes [pl. 8, fig. 5] and lacustris. They 
inclose here a distinct smooth, flat median zone, which corresponds to 
the course of the intestine and there is reason to believe that this 
double series of scales marks the bases of the muscles and suspensory 
organs of the intestine. In Pterygotus the distal portion of the intestine 
+The muscles of the eurypterid cephalothorax were probably contracted 
into solid bundles, as in Limulus, following the solidification of the segments. 
This is indicated by the occurrence of a pair of entapophyses, or chitinous infoldings 
of the carapace [pl. 6, fig. 6], corresponding in their position to those observed 
in Limulus, and also by the observation of 
pairs of circular or oval areas arranged along 
the median line. At least three such pairs 
of areas have been seen in Eurypterus 
remipes. The foremost of them is shown es = 
CBB 00Ry- .-€ 
in plate 5, figure 7. They may correspond to 
the first pair of tergo-proplastrals in Limulus 
which suspend the anterior horns of the ento- 
sternon from the dorsal side of the carapace. 
Gaskell has drawn a hypothetical restoration 
of the muscle system of the cephalothorax of Figure 4 Dorso-ventral muscles on carapace 
an Eurypterus [text fig. 4] by inserting in of Eurypterus 
le, lateral eyes; ce, ocelli; 62, median dorso- 
. preoral-entosclerite muscle; 63, anterior 
mental dorso-ventral muscles as met with in dorso-plastron muscles; 64, median dorso- 
plastron muscle. (From Gaskell) 
the carapace of E. scouleri the seg- 
the living scorpion. In a general way this . 
is corroborated by our observations, with the exception that the muscles do not 
appear to be arranged so closely around the center of the carapace, at least in 
E u rypterus remipes. From evidence presented subsequently it would seem 
preferable to use Limulus as the basis of such restoration. 
