Page:The Eurypterida of New York Volume 1.pdf/259

  as here defined unquestionably belonged to the giants of the race and lagged little, if at all, behind   in size. Not less than three of the few specimens known indicate individuals of two feet or more in length.

The species differed from  in being built still more compact and sturdy. This is shown in the relatively shorter and broader preabdomen, the shorter and especially broader postabdomen and the shorter, stouter and probably straight telson. The posterior contraction of the preabdomen is more abrupt and the outline of the preabdomen and carapace combined more broadly oval posteriorly. The walking legs are stouter and provided with longer spines; the swimming legs reach farther back (principally on account of the greater contraction of the preabdomen) and the postabdomen is notably broader. The cephalothorax has grown somewhat in proportion to the body, probably on account of the greater stoutness of the appendages for which it has to serve as basis of attachment.

Clarke. N. Y. State Mus. Bul. 107. 1907. p. 307, pl. 5, fig. 10; also pl. 5, fig. 7

Description. The original description of this species which was based on a single specimen is:

This diminutive head shield is remarkable for the extraordinary development of the compound eye lobes which are anterior and very prominent and though the shield has a diameter of only 4.5 mm, the ocellar mound is fully developed. So unusual is the aspect of this specimen that it can not be assigned to any of the other species here noted, and though entirely immature, it is given a distinctive designation.

Later collections have furnished a few more specimens of like size exhibiting the same unusual characters as well as somewhat larger specimens which would indicate, if properly referred here, a remarkable change of characters in the ontogeny of this form. We shall first describe the type and then note the later changes.