Page:The Habitat of the Eurypterida.djvu/172

164 :Pachytheca
 * Parka n. sp.
 * Fucoid-like markings

One of the two best localities for ichthyolites and the one in which all of the species of Downtonian fish determined by Dr. Traquair have been found is in the Slot Burn, one of the tributaries of the Greenock Water. The fossils thus far described from there are (215, 578):


 * Eurypterus dolichoschelus (Laurie)
 * Stylonurus ornatus (Laurie)
 * Myriopod
 * Lanarkia spinulosa (Traq.)
 * L. horrida (Traq.)
 * L. spinosa (Traq.)
 * Thelodus scoticus (Traq.)
 * Birkenia elegans (Traq.)
 * Lasanius problematicus (Traq.)
 * Ateleaspis tessellata (Traq.)
 * Ceratiocaris laxa (Jones & Woodw.)
 * Dictyocaris sp.
 * Pachytheca sp.
 * Plant stems.
 * Sponge?

A second fish band yielding several species of fishes and a myriopod has been found a short distance up the Slot Burn and at a slightly higher horizon than the main one; eurypterids have not yet been found in it.

An excellent section in the eastern area of the Lesmahagow anticline is shown in the Birkenhead Burn, a tributary of the Logan Water. The passage from the Ludlow to the Downtonian is obscured by a normal fault which abruptly truncates the Ludlow series, but the rest of the succession is complete. The total thickness of the fish-band with the intercalated mudstones is here fifteen feet. The lowest fossiferous carbonaceous seam is about a foot thick, while higher up in the band the seams vary from one to six inches. "The remarkable feature of this exposure is the constant association of the fish fauna with eurypterids that are characteristic of the underlying Upper Ludlow rocks." The fossils listed are (215, 580):