Igo NEW YORK STATE MUSEUM 
Remarks. In aspect, Eurypterus maria is greatly differ- 
ent from all its American congeners. This is largely due to the terete 
form of the body that apparently is without preabdominal expansion. A 
few specimens [pl. 22, fig. 8] indicate that there was a slight expansion, 
but it seems to have found its expression mostly in an increased vertical 
convexity of the body. This convexity both of the dorsal and ventral 
sides producing the subcircular section of both preabdomen and _post- 
abdomen, is shown by several specimens which are but slightly compressed. 
A species quite similar to our type in both form of body and size is 
E. pygmaeus Salter from the Downtonian (uppermost Ludlow) of 
Great Britain. Its carapace, however, seems to have been a little longer 
Figure 37 Eurypterus maria Clarke 
I~V States of preservation affecting the outline of the carapace and the size and position 
' of the compound eyes 
and the eyes a little more forward in position. From the other species 
of Eurypterus these two forms differ in their long, gradually tapering, 
terete body and the small size of the swimming legs. | 
The variability in the size and position of the eyes is commented 
upon in the preliminary description. Note might also be taken of the 
confusing variability in the outlines of the carapace. A survey of a great 
number of carapaces shows that the variability of features which in other 
species exhibit considerable stability, is for the most part due to the great 
convexity of the carapace of this species and the resulting various modi- 
fications under the influence of differing directions of compression. The 
accompanying text figures are inserted to illustrate this fact. In figure 
I the carapace has been vertically and gradually compressed so that 
the eyes are projected on the horizontal plane directly below their origina} 
position. The uninterrupted concentric wrinkles and the normal size of 
