162 THE HABITAT OF THE EURYPTERIDA 



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 collec- 

 tions. 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 log'ani (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 Home's subdivisions have yielded eurypterid remains in the basin 



