200 NEW YORK STATE MUSEUM 
Eurypterus (?) (Dolichopterus?) prominens Hall 
Eurypterus prominens Hall. Am. Ass’n Adv. Sci. Proc. 1884. 33: 420 
Eurypterus prominens Hall & Clarke. Palaeontology of New York. 1888, 
7: 157, pl. 27, fig. 3, 4 
This species, the single eurypterid representative from the Clinton group, 
is based upon a carapace that was fully described by Hall and Clarke. 
These authors also point out the characters by which this species is dis- 
tinctly different from any other species of Eurypterus. The most impor- 
tant of these is the anterior position of the eyes, 
which coupled with their submarginal position and 
the great length of the carapace (length to width 
as 27:30 or 9:10) gives the latter an aspect very 
like that of Dolichopterus, so that it would not 
be surprising if later discoveries prove this species 
closely allied to that genus. In Dolichopterus the 
specialization has gone a step farther and the cara- 
pace, which there is still well rounded at the anterior 
corners, has become subquadrate. 
Figure 38 Eurypterus? It may be also mentioned that the youngest 
prominens Hall. Orig- 2 
oo aoe (From Hall stage of E. remipes observed has the same long 
carapace and anterior eyes and that, for this reason, 
E. prominens may represent a phylogenetically youthful type of 
Eurypterus, an inference that is supported by the geologic position of 
the species. 
The ocelli have, as usual, followed the compound eyes and are situated 
well forward on a line connecting the posterior extremities of the lateral 
eyes. They mark the apex of the carapace. The uncompressed type 
specimen shows this head shield to have been relatively high, but its summit 
flattened and culminating in a broad ridge connecting the compound eyes. 
The oblique linear depressions on the postlateral areas are rather 
faint and somewhat exaggerated in the drawing. Similar depressions 
