THE EURYPTERIDA OF NEW YORK 47 
Zittel’s Handbook and in textbooks, will make this point clear. In the 
former they are represented as attached to the foremost point of the under- 
side of the cephalothorax; in the latter they appear as inserted just in 
front of the mouth at the base of the epistoma. Schmidt says regard- 
ing this point [p. 73]: ““ Um auf die Scheerenftthler zuriick zu kommen, so 
hatte ich ihren Ansatzpunkt gern, wie meine Vorgdnger, nach vorn an 
der Unterseite des Kopfes verlegt, aber die eben besprochene 3-theilige 
Umschlagsplatte liess eine andre Auffassung nicht zu, als ich sie oben 
auseinandergesetzt. An ihrer Oberflache ist nirgend ein Platz fur den 
Ansatz der Scheerenfithler und zugleich war fur diese Umschlagsplatte 
selbst keine andre Deutung moglich.’”’ Laurie has not critically discussed 
this question in his study of the eurypterids, but only suggests that there 
was perhaps no properly developed articulation between them and the 
epistoma because they are always found torn off. 
| While we are not in a position to offer direct evidence on this problem, 
or at least only such as is inconclusive, we believe in the correctness of 
Schmidt’s inference for the following reasons. One of our specimens 
shows that the six appendages of one side radiate from one point, which 
would mean that the chelicerae were inserted directly in front of the first 
pair of walking legs. But aside from this observation, the fact that the 
attachment of the chelicerae, in Slimonia, Eurypterus and Hughmilleria, 
has since been fully established to be directly in front of the mouth as in 
Limulus, leaves little doubt that the large pincers of Pterygotus, 
if they are at all homologous to the minute chelicerae of those three 
genera, must have had the same place of insertion, viz, at the posterior 
end of the epistoma. We may add that the homology of the large 
pincers of Pterygotus with the chelicerae of Limulus, Eurypterus etc. 
would also suggest as an a priort conclusion, their composition of but 
three segments and the lack of a distinct articulation with the epistoma. 
. The general conclusion from the foregoing observations is that the 
chelicerae exhibit a remarkable identity of structure in all genera despite 
their great differences in relative size. | 
