THE EURYPTERIDA OF NEW YORK 241 
the following, the palette. It is subrectangular in general outline, its 
length is one fifth longer than the width, the proximal and distal sides 
both deeply notched for articulation. The upper angle of the proximal 
side is evenly rounded, the lower much produced to meet a corresponding 
notch in the preceding segment. The lower part of the distal side is produced 
into a triangular plate about one third as long as the segment and sepa- 
rated from it by a transverse suture. The other upper part of the distal 
margin is nearly straight. The eighth segment is a very long oval, twice 
as long as wide, the distal end being the more slender. The terminal 
segment is subcircular in outline and relatively large. 
The metastomais heart-shaped 
in outline and relatively short. 
The frontal margin is the longest; 
it seems to be slightly emarginate, 
but the preservation is not clear 
enough to determine this point. 
Length and width of plate nearly 
equal. The antelateral angles are 
well rounded and the sides contract in a gentle curve to the blunt pos- 
terior extremity. | 
Genital appendages. Ofthese only the female have been seen in two 
examples. In the older of the two the appendage begins with two triangu- 
lar (or subpentagonal) basal members, not seen in the younger individual, 
as the sutures which separate them from the opercular plates are not 
developed. These plates inclose an elongate sagittate base similar in shape 
to that of Pterygotus buffaloensis. At the posterior angles 
of the latter two semicircular lobes are observable which probably covered 
the genital openings. From it proceeds the slender middle portion which 
is convex along the median line and flat along the borders. The distal 
extremity is seen in the younger specimen. Here it consists of two con-. 
Figure 58 Diagram of dorsal view of left swimming leg 
verging obtuse pieces with parallel inner and converging outer sides. The 
basal portion which is sagittate in the older individual is rounded or in- 
