THE EURYFTERIDA OF NEW YORK 265 
Hall fully recognized that the last postoral limb differs from the cor- 
tesponding organ of all other eurypterids in the development of the ninth 
segment into a broad expansion like an oar blade. These last limbs are 
not only very long, for when fully turned back they would have nearly 
reached the penultimate postabdominal segment, but also rather flexible 
and expanded in all segments, most markedly however in the last four. 
The coxa of this leg, which is fairly well shown in thetype and still 
better in the specimen from Litchfield, differs in outline from those of 
other eurypterids being much longer in anteroposterior direction.’ 
The coxa is ‘subrhomboidal in shape (its short posterior side only 
half as long as the long inner edge), with a long curved neck leading to 
the manducatory edge. The second and third segments are short, ringlike, 
especially so the third, while the fourth is distinguished from all others 
by its length, it being twice as long as each of the two following segments 
and four times as long as the preceding one. It is twice as long as wide. 
The fifth and sixth segments are of subequal dimensions, each nearly one 
fourth longer than wide. The seventh and eighth segments are broad and 
relatively short, their longitudinal and transverse diameters being about 
equal. Their outer edges are obscurely serrate. The lobe of the seventh 
segment which is narrowly triangular in Eurypterus, is here produced into a 
leaflike process, which in length equals the segment. The eighth segment, 
which is the palette in Eurypterus and Pterygotus, is in this genus of similar 
form as the preceding segment. The ninth segment, the small “claw” in 
other eurypterids, has here assumed the bladelike shape of the eighth seg- 
ments in Eurypterus and Pterygotus. It is oval in shape, with its extremity 
somewhat drawn out, longer than the preceding segments, one and one half 
times longer than wide. Its outer margin is coarsely serrate, the ser- 
rations directed obliquely forward and convex on the outer side. The 
metastoma has been described by Hall as “‘lyrate, with the anterior margin 
1 This elongation is of course shared by the metastoma and obviously induced by 
the relatively great length of the carapace. But the mouth is further forward in 
this species than in other genera. 
