Page:The Eurypterida of New York Volume 1.pdf/414

, and it is probable that this generic term will have an independent value, for though the telson in its outline is certainly comparable to that of certain species of Pterygotus, as   Woodward, its section is totally different from that of any of the Pterygotidae and the fragment of segment indicates a different inclination of the side of the body than is observable among other pterygoids.

Among the remarkable remains which have been described by Dr C. D. Walcott from the Cambric is a wonderful arthropod, which has been brought to public notice just as this work is completed.

This organism is extraordinary in the preservation of its anatomy and as both it and its associate,, are referred by Dr Walcott to the Merostomalta, they invite brief notice in this place. Both are from the Middle Cambric (Stephen formation) of British Columbia.

is based on a fragmentary portion of an abdomen and for this reason will not be included in our annotations. These refer entirely to the splendid material secured of the species.

Sidneyia and Amiella are united in a new suborder  of the Eurypterida.

The suborder is described as follows:

Body elongated with a thin epidermal skeleton either smooth or ornamented by lines or ridges. Cephalothorax with lateral or marginal eyes, on the ventral side with five pairs of movable appendages; mouth posterior to a large epistoma.

Abdomen with twelve segments, the anterior nine of which have a pair of ventral appendages to which the branchiae are attached; the posterior segment has a central spatulate-shaped section that, combined with swimmerets, forms a strong caudal fin.