186 | NEW YORK STATE MUSEUM 
The first tergite 1s considerabiy shorter than the others. It is six to seven 
times as wide as long; the following ones are about four times as wide 
as long. 
The sternites are less straight bands than the tergites, their middle 
portion curving forward more distinctly. Their antelateral angles are 
produced into broad rounded ears or lobes, while the postlateral angles 
are well rounded. The operculum has not been observed. | 
The postabdomen tapers uniformly to the posterior extremity which 
is but one third as wide as the anterior. The segments are all circular 
in section, and they gradually become longer while they diminish in width, 
the first segment being four times as wide as long, while in the last the 
width is to the length as 3: 4. The segmental rings are very simple with 
but very inconspicuous lateral flanges in the first segments and none in 
the last. 
The telson is bluntly lanceolate; at the base it, is three times as wide 
as long. Its dorsal side is convex and raised into a median keel; the 
underside flat and the lateral margins are furnished with sharp, blade- 
like edges. : 
Appendages. In spite of the great number of heads found only the 
swimming legs have been observed In mature specimens [pl. 21, fig. 11] 
these are remarkably short and protrude but little more than half the 
basal width of the carapace. The eighth segment (the palette) is long, 
elliptical, the ninth forming a small terminal claw. Of the seventh seg- 
ment but a portion has been seen protruding from below the carapace and 
this indicates that it was considerably narrower than the following ones. 
Ornamentation. No scales or tubercles have been made out on either 
the carapace or abdomen. The only traces of ornament observed are a 
median transverse line on both the sternites and tergites, with traces of 
more lines n the latter, especially near the anterior margin. 
Ontogeny. In its ontogeny Eurypterus maria includes .a 
larval stage that is not only strikingly different from the mature but also 
highly suggestive phylogenetically by its great similarity to Strabops. 
