THE EURYPTERIDA OF NEW YORK BAS 
segments form a slightly expanded oar plate, the seventh being slightly 
longer than the eighth and bearing a large distal lobe on the inner side. 
The eighth segment is oval in form, its distal end distinctly acute with 
a small terminal subcircular ninth segment [pl. 65, fig. 8]. 
The coxa of the last pair of legs is probably represented by figure 1, 
plate 66, for these bodies show the outline of the corresponding organ in 
the genotype and possess a system of fine anastomosing lines characteristic 
of the sculpturing of H. shawangunk. Sarle compares the shape of 
this coxa in H. socialis to that of an upright retort and records the 
presence of 18~20 sharp, slightly curved teeth on the manducatory edge. 
The coxa here figured exhibits a stronger neck and longer manducatory 
edge, but exactly the same number of teeth. Another coxa, reproduced 
in the preliminary paper [op. czt. pl. 8, fig. 10] also possesses a system of fine 
lines as shown in our figure [pl. 66, fig. 2] but is of more compact form and 
with shorter neck and smaller number of teeth, the first of which is longer 
than the rest. This is possibly the coxal joint of an endognathite. 
The metastoma has not been seen well preserved in position, but we 
refer several metastomas to this species [pl. 66, figs. 3, 4] because they 
possess, on one hand, the form of that in H. socialis andon the other 
exhibit a peculiar striated ornamentation apparently characteristic of 
H. shawangunk. These metastomas are elongate cordate, broadest 
anteriorly to the middle, with cordate or deeply notched anterior and an 
evenly rounded posterior extremity in some and a truncated one in other 
specimens. 
The genital appendages have not been seen. 
The ornamentation is most characteristic. It consists on all segments 
of a series of fine striae, running parallel to the anterior margin, most 
crowded near this margin, farther apart and fainter posteriorly, disappear- 
ing at about the middle of the segment, save on the postabdominal 
segments where they can be traced to near the posterior edge. Near 
the lateral edges of the tergites they bend sharply backward, finally 
coalescing with the border and gradually disappearing. On the sternites 
