the fact that the European species P. bilobus, P. anglicus and P. barrandei, which possess similar rounded free rami and have afforded the entire chelicerae, also demonstrate that the fixed ramus is correspondingly formed, and that these characters of the chelicerae appear even in younger individuals. We insert here a sketch of the chelicera of P. barrandei, whose free ramus possesses the greatest similarity to that of our type, in order to show the probable form of the entire chelicera of P. cobbi.
 Figure 79 Pterygotus barrandei Semper, here introduced for comparison. Natural size. (From Seeman) |
The second suggestion, above advanced, that P. cobbi may be only a variety, is also refuted by the evidence from the European material, which demonstrates that the chelicerae are very good indicators of specific distinction. The chelicerae of the P. buffaloensis-macrophthalmus group are almost identical with those of P. bohemicus Barrande, while those of the associated P. cobbi correspond closely to those of P. barrandei Semper, found with bohemicus in the Bohemian Upper Siluric stage.
