Page:The Habitat of the Eurypterida.djvu/182

174 alternating sedimentary and igneous rocks which were contemporaneous in their development with the main volcanic outpourings (see sketch map, fig. 17).

The first important fossiliferous beds are those found at Carmylie and adjoining localities in Forfar. These constitute a part of the famous Arbroath flags and because of their abundant eurypterid

remains are called the Pterygotus beds. In them are found the most perfect specimens of Pterygotus anglicus, though complete individuals are rare, and the rock often contains also an abundance of Parka decipiens, which has been variously identified as crustacean egg cases and as spores of plants. Above these beds follows the main mass of the lavas upon which rest the beds of Auchtertyre, which