8 POST-TERTIARY ENTOMOSTRACA. 



exceptional cases, far less distinctly striated. The Arctic shells found scattered through 

 it, although chiefly in single valves and broken, are decidedly better preserved than in 

 the fossiliferous Boulder Clay just described. A Leda, indeed, has been found vk^ith both 

 valves united, and the bed contains species as characteristic of the ordinary Glacial Clays 

 as Peden Islandicus, Astarte borealis, Leda pernula, Cjjprina Islandica, together vv^ith 

 Foraminifera and Ostracoda. Patches of sand and gravel are common. This clay is 

 evidently the wash of an old Boulder Clay upon a somewhat exposed coast. The angular 

 blocks have been jumbled together, their striations half obliterated, and their polish 

 somewhat worn off, while the clay has been washed and rewashed around them, and a 

 rude and rough habitat formed for the scanty development of a marine fauna. In an 

 account of these beds given by Dr. Bryce and one of the authors of this paper,^ it is 

 pointed out that the upper part of the shell-bed is a little sandy, while in the lower part 

 the character more closely approximates to the underlying Boulder Clay.~ 



The following Ostracoda were found in the shell-bearing clay, of the character now 

 described, on the banks of the Cloinid Burn, near Lag Arran. A complete section of 

 the bank will be given as we proceed to notice the next division of so-called Boulder 

 Clays: 



Cythere joellucida, Baird. 



— concinna, Jones. 



— Chttha, nov. sp. 



— emarginata (G. 0. Sars). 



— Dunelmensis (Norman). 

 Cytlteridea punctillata, Brady. 



— papulosa. Bosquet. 

 Cytherura nigrescens (Baird). 



— undata, G. O. Sars. 

 Cytheroptero?i nodosum, Brady. 



IV. A series of deposits composed of sand, gravel, and clay, and containing boulders 

 often in large numbers, must be carefully discriminated from the " Boulder Clay " of this 

 paper. 



Instead of the innumerable finely polished and striated stones characteristic of the 

 " Boulder Clay," these beds contain stones with coarsely worn surfaces and half oblite- 



1 ' Arran and other Clyde Islands,' by J. Bryce, LL.D., 4th ed., p. 184. 



2 A different view of this clay is taken by the Rev. R. B. Watson, B.A., in his paper " On the Great 

 Drift Beds with Shells in the South of Arran," ' Trans. Royal Soc. Edin.,' vol. xxiii, p. 523. 



