1 64 THE HABITAT OP THE EURYPTERIDA 



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 anti- 

 cline 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 

 fossiliferous carbonaceous seam is about a foot thick, while higher 

 up in the band the seains vary from one to six inches. "The remark- 

 able 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) : 



