Page:The Habitat of the Eurypterida.djvu/234

226 two fragments. The carapace looks as though it might well belong to a large Hughmilleria; at any rate it has no close affinities to any other species. Similarly, little of correlative value can be deduced from Stylonurus multispinosus which is known only from a group of endognathites. In their characteristics they are different from anything in the Bertie (39, 297), and are of little relational value.

It will be shown below (p. 232) that E. pittsfordensis is closely related to E. lacustris in the Bertie, but as will be seen, this is entirely expectable.

In the Shawangunk fauna the most abundant species is Hughmilleria shawangunk whose relationship has been discussed under the Pittsford fauna. The very rare forms, Eusarcus (?) cicerops, Dolichopterus stylonuroides, Stylonurus myops, and Pterygotus globiceps, represented by only a few fragments, show no particular relation to species in any other fauna. Indeed, a comparison of the young of E. scorpionis with the young of E. cicerops shows that the cephalon was very different in outline and the position of the eyes was not at all similar (Clarke and R., 39). Similarly, Stylonurus cestrotus, found only in a fragmentary condition, "stands apart from all its allies in a number of characters that show it to be an aberrant form" (39, 291) Eurypterus maria, of which many young and one or two mature individuals have been found, is "greatly different from all its American congeners," (39, 190). The relations of Dolichopterus otisius have already been pointed out, and it has been shown that while it agrees in certain characteristics with one species, in others it agrees with a different one, so that its affinities cannot be said to be with any particular fauna.

Summarizing the evidence offered in a comparison, species by species, it becomes clear that the dominant, most abundant species in the Pittsford and Shawangunk faunas are alike and that there is only one form in either of these which shows relationship to a Bertie species.

. The following points may be briefly recapitulated: 1. In the sediments which it has been demonstrated (by myself or others), were with more or less certainty derived from Appalachia, the eurypterids are either unique, showing no relation to known species in North America or other continents, or else they show phyletic relationship inter se, the species of later faunas having certain characteristics in common with those of (generally the mature forms of) earlier faunas.