Page:The Eurypterida of New York Volume 1.pdf/227

 of the genus and in this evidence of waning racial characters it invites special recognition. The Pennsylvania species to which we have referred are  C. E. Hall,   C. E. Hall,   J. Hall and   Hall & Clarke. These species, together with     are distinguished from Eurypterus proper by the following features: (1) the character of the spines of the endognathites, seen in , in   and  , (2) the development of the scales into mucros, giving the greater portion of the surface a spinous appearance. This tendency to spinosity, especially of the posterior margins of the abdominal somites is also present in British Carbonic forms, as is amply evidenced by   Woodward with its long pointed scales,   (?)   R. Etheridge jr [Geol. Soc. Lond. Quar. Jour. 1877. 33:223] in which the surface is covered with long blunt spines and scales, giving it the appearance of a mass of congealed drops, while in  H. Woodward the scales have become prominent wartlike tubercles, interspersed with disklike bodies which proved to be "calculi" or bodies of globular calcite formed inside the integument. All these excrescences are distinctly phylogerontic and seem to indicate that