l6o PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Lower Palaeozoic rocks were they so largely presented, and all the 

 known forms in the Wenlock group (11 genera and 24 species) 

 occur in the Wenlock Limestone and Shale, and in those of England 

 alone, only 1 species occurring either in Scotland or Ireland. 



Protozoa. — Cliona prisca and Spongarium Edwardsii are both 

 Denbighshire-grit species, the latter being also Wenlock and Lud- 

 low ; Cnemidium tenue occurs in the Wenlock only, and Ischadites 

 Grindrodi in the Woolhope ; the other well-known species, I. 

 Kosnigi, Murch., has a wider range both in time and space, and has 

 occurred in the Wenlock rocks beneath the Cretaceous series at 

 Ware, in Herefordshire, in the Silurian cores brought up from a 

 depth of 1000 feet, during trials for the better supply of London 

 with water. 30 Wenlock species were obtained here from a few 

 feet of cores ; they are identical with the Wenlock species of Dudley 

 and Wenlock Edge. (Vide page 229, in the Chapter upon the 

 extension of the older rocks under the London area.) The singular 

 and still doubtful genus Stromatopora ($. striateUa) occurs plentifully 

 in the shales and limestones of the true Wenlock beds, and is also 

 found in the Aymestry Limestone. This genus comprises a large 

 number of Silurian and Devonian fossils of every size and form. The 

 affinity of the Stromatoporids is still doubtful ; by some authors they 

 are placed with the Hydrozoa, in the subclass " Hydrocorallina." 

 The doubtful Devonian genus Caunopora suggests much research, 

 both from its abundance and peculiar structure. In Britain Stroma- 

 topora first appears in the Caradoc and Bala group, ranging upwards 

 into the Middle Devonian of Devonshire. 



Hydrozoa. — The Wenlock rocks (assuming the Tarannon and 

 Denbighshire beds to be at their base) have yielded 6 genera and 30 

 species. Stratigraphically they occur chiefly in the Tarannon beds, 

 or probably the Denbighshire Grits. So far as I know there are 

 none in the Woolhope beds, and I omit them from the column 

 headed W enlock, as they occur chiefly at Builth and in North Wales', 

 and in this case would be repeated. The Tarannon or Denbighshire 

 beds have yielded 5 genera and 23 species ; North Wales 1 genus 

 (Monograptus) and 8 species ; South Wales 3 genera and 15 species ; 

 Westmoreland 3 genera and 16 species ; Scotland 3 genera and 5 

 species. 



Actinozoa. — At no period during the progress of Palaeozoic time 

 was there so large and rich a Coralliferous fauna as during the 

 Wenlock period ; numerically the Middle Devonian about equalled 

 the Wenlock species in number, the genera and species being in both 

 deposits much the same. The Wenlock rocks of Britain yield 25 

 genera and 76 species, the Devonian 24 genera and 52 species, 

 and the Carboniferous 36 genera and 141 species. 



I believe every known Wenlock species (there are 76 of them) 

 occurs in the Wenlock Limestone and its subordinate shales. In the 

 lower division, especially the Tarannon Shale and the Denbighshire 

 Grits, the species are few, not more than five being known in the 

 former and four in the latter. 



