242 TRANSACTIONS, NATURAL HISTORT SOCIETY OF GLASGOW. 



Burn, near Crawford, owing to rapid denudation, the chert-shale 

 is of a fine fresh green colour, with very few Conodonts; but 

 here one sometimes finds Radiolarians in it wath the spines 

 attached, and occasionally showing the double cancellated test. 

 In the Hunt Law Cleuch the chert-shales are yellowish, greyish, 

 and bluish, and, as already remarked, there are Conodonts in 

 every layer, the chert bed here, although " erected " at right 

 angles to its original position, having suffered very little from 

 crushing. In the grey chert-shales of FardingmuUoch, Cono- 

 donts are common; in the green ones, very rare. In the grey 

 shales the Radiolarians have sometimes the spines attached. 



In the dark-grey chert-shales of Morroch Bay, south of Port- 

 patrick, north and south sides, I obtained a few from the south 

 bed and one from the north bed. The shales here sometimes 

 show a tinge of green, and have occasional Radiolarians, with 

 spines attached. 



I could find no specimens in the chert-shale of the Spotfore 

 Burn, a tributary of the Crawick Water, the shale being much 

 crushed and containing an extra quantity of mica. Similar 

 remarks apply to those of the Kiln Burn, another tributary of 

 the " Crawk." 



All the samples I brought from the Whing Burn, a tributary 

 of the Euchan, near Sanquhar, were totally unfit for micro- 

 scopic examination. 



At the base of Arbory Hill, on the left bank of the little 

 stream called Raggen Gill, a tributary of the Clyde, near 

 Abington, I did not see any Conodonts in the chert - shale. 

 Further up the gill than this exposure there is an immense 

 quantity of chert — red, green, and grey — forming a talus-slope 

 on the side of the glen, but only small knobs of the solid beds 

 are exposed, and, as the shale when separated from the chert 

 is soon reduced to clay by weathering, no material could be 

 obtained here. 



As to what Conodonts are, these Arenig-Llaudeilo ones, I 

 think, throw, no further light on the subject. It has been 

 conjectured that they may have been the teeth which armed 

 the odontophores of naked gastropods. In recent gastropods 

 the odontophores have generally three rows of teeth, the 

 two outer being " rights and lefts," the central row consisting 



