Page:The Eurypterida of New York Volume 1.pdf/415

 The description of the branchiae will be found under the description of Sidneyia, the typical genus of the Limulava.

Observations. The suborder Limulava differs from the Eurypterida, to which it is most nearly related, in having a large epistoma similar to that of the Trilobita; in not having a metastoma, chelate antennae, and swimming cephalic appendages; and in having a broad, fan-shaped caudal fin, and branchial appendages more or less unlike the lamellar branchiae of the Eurypterida and Xiphosura.

The relations of the order and suborder are shown in the following tabular view:

In view of the unusual structures here set forth it is germane to this work to inquire whether these Limulava should be construed as belonging to the Eurypterida in the capacity of a suborder or if they may not more properly assume a higher grade as an independent and coordinate group.

The Eurypterida, as represented by the genera hitherto referred to them, constitute a very compact order with well fixed characters. If