424 NEW YORK STATE MUSEUM 
pionis or Eusarcus in general, which is properly considered as a very 
aberrant eurypterid genus. But while the species is in almost all features 
an E. scorpionis, its distinctive characters are such as would 
indicate a still higher degree of aberrancy than seen in the considerably 
younger E. scorpionis from the Bertie waterlime. The most im- 
portant of these characters are the tonguelike anterior process of the cara- 
pace and the position of the ocelli between the lateral eyes. The first 
would seem to be a further advanced adaptation to the mud-grubbing 
habit of the species, the snout being used as a digging and perhaps also a 
feeling organ.t The second character, the forward position of the ocell1 
in distinction of the still central position in E. scorpionis [see 
pl. 29] would also seem a further advance in the anteriorly raised carriage 
of the carapace peculiar to Eusarcus and indicated by the position of the 
lateral eyes and the forwardly progressing length of the walking legs. 
Eusarcus cicerops, an Otisville species, has these two fea- 
tures, the anterior process and the forward position of the ocelli, in common 
with E. vaningeni. The former, in the position of the lateral eyes 
and the broad base of the carapace, seems closely allied to E. vanin- 
geni, and as our specimens of E. cicerops are all of early growth 
stages, it is possible that the mature specimens were still more like 
E.vaningeni. The presence of these two closely related aberrant 
types in the lowest Salina beds of Oneida county and in the Shawangunk 
shale, strengthens our inference as to the probable equivalence of the 
Shawangunk grit with the Pittsford shal. Eusarcus nasutus 
1 The fact that this process is more or less bent downward in two of the specimens 
might lead to the assumption that it is homologous to the epistoma of Pterygotus and 
might have been bent under entirely. Several considerations disprove this assump- 
tion, namely, the absence of a suture separating it from the anterior part of the cara 
pace and the passing of the filiform thickened border around the process; and above 
all, the existence of another species of Eusarcus (EH. cicerops) with a similar 
but much less developed anterior process [see pl. 36, fig. 3, 4] which is clearly a straight 
extension of the carapace. 
