Page:The Habitat of the Eurypterida.djvu/170

162 :Slimonia acuminata Salter
 * Physocaris sp.
 * Pterinea retroflexa Wahl.
 * Platyschisma (Trochus) helicites Sow.
 * Thelodus scoticus Traq.
 * Thelodus planus Traq.
 * Fish fragment undetermined

Overlying the Ceratiocaris beds and appearing as a narrow band to the north of them throughout the area is a series of hard blue and grey flaggy shales and mudstone, with occasional calcareous nodules. These constitute the Pterygotus beds, 350 feet thick, and are the ones from which Dr. Slimon of Lesmahagow made his extensive collections. The best section is along the Logan Water which for quite a distance runs along the strike of the beds. On the right bank about 400 yards west of Dunside the following fossils have been collected (215, 575):


 * Ceratiocaris papilio (Salt.)
 * Neolimulus falcata (Woodw.)
 * Eurypterus lanceolatus (Salt.)
 * Eurypterus obesus (Woodw.)
 * Eurypterus scorpioides (Woodw.)
 * Pterygotus bilobus (Salt.)
 * Pterygotus bilobus var. acidens (Woodw.)
 * Pterygotus bilobus var. inornatus (Woodw.)
 * Pterygotus raniceps (Woodw.)
 * Slimonia acuminata (Salt.)
 * Stylonurus logani (Woodw.)
 * Lingula minima (Sow.)

"In a small tributary of the Logan Water from the north, at a spot about 250 yards west from Dunside, these flaggy shales have yielded specimens of Spirorbis lewisi, Beyrichia kloedeni, Dictyocaris slimoni, Pterygotus bilobus, Slimonia acuminata and Platyschisma helicites."

In several others of the tributary burns the eurypterids are found associated always with Ceratiocaris or Dictyocaris, Beyrichia kloedeni usually and sometimes lingulas.

Still higher horizons of the Ludlow, numbers 5 and 6 of Peach and Horne's subdivisions have yielded eurypterid remains in the basin