46 



PALAEONTOLOGY. 



Minute Ostracoda, related to the recent Cypris (fig. 10, 5), 

 swarm in the laminated fresh-water clays of the "Weald en | 

 whilst the marine Cytheridce assist with their multitudinous 

 atoms in building up the chalk. Amongst the Phyllopods, the 

 gregarious Estheria covers the slabs of Wealden and of Keuper 

 with crowds of bivalve shells which have been commonly mis- 

 taken for Cyclades and Posidonomyw. Estheria abounds in the 

 Caithness flags of the middle Devonian series. The globose 



Fig. 9. 



Palceozoic Entomostraca. 



1. Leperditia Baltica, Wahl. ; U. Silurian, Gothland. 



2. Entomoconchus Scouleri, M'C. ; Carboniferous, Ireland. 



3. Beyrichia complicata, Salter; L.Silurian, Wales. 



4. Dithyrocaris, Scouleri, M'C. ; Carboniferous, Ireland. 



5. Pterygotus Anglicus, Ag. ; Old Red Sandstone, Ludlow. 



6. Bellinurus bellulus, Konig. ; Carboniferous, Coalbrookdale. 



7. Ulsenus Davisii, Salter ; L. Silurian, Bala. 



8. Phacops caudatus, Brun. ; U. Silurian, Dudley. 



9. Calymene Blumenbachii, Br. ; U. Silurian, Dudley, 

 [o. Trinucleus ornatus, Sternb. ; L. Silurian, Britain. 



1. Agnostus trinodus, Salter; L. Silurian, Britain. 



Entomoconchus (fig. 9, 2) is found in the carboniferous lime- 

 stone ; Leperditia (fig. 9, 1) in the Silurian rocks of the north ; 

 and Beyrichia (fig. 9, 3), which is characteristically Silurian, 



