ANNIVEESAEY ADDEESS OF THE PEESIDENT. 175 



Lower Ludlow. The whole Crustacean fauna, therefore, of the 

 Ludlow rocks is 29 genera and 97 species. The Lower Ludlow 

 contains 18 genera and 47 species, the Aymestry Limestone 9 genera 

 and 12 species, and the Upper Ludlow 23 genera and 71 species. 

 The Passage-beds into the Old Eed Sandstone have yielded 9 genera 

 and 15 species, 4 being Ostracoda, 1 Phyllopod (Ceratiocaris decorus), 

 and 10 Merostomata (Eurypteridse). No Trilobite occurs in the 

 Passage-beds. This Passage-bed Crustacean fauna is what we 

 should have anticipated ; the Brachiopoda and Mollusca proper show 

 the same indications of a change from a deeper to a shallow coast- 

 line, and a fauna struggling to maintain life against new and adverse 

 conditions. Shropshire through the Ludlow area possesses 18 genera 

 and 46 species, Worcestershire 17 genera and 25 species, Hereford- 

 shire 14 genera and 26 species, Westmoreland 8 genera and 15 

 species. Scotland, chiefly through the Phyllopoda and Merosto- 

 mata, has 12 genera and 22 species. Ireland only possesses 2 

 (Calymene Blumenbachii and Phacops caudatus). This deficiency of 

 the Crustacea in Ireland, as indeed of all the classes except the 

 Brachiopoda, bears out the fact of the smallness of the Ludlow 

 fauna in Ireland. I am obliged to carefully detail the number of 

 genera and species that range through and enter into the distri- 

 bution of the Crustacean fauna on account of its peculiarities. 

 13 new genera made their appearance during the Ludlow period. 

 4 Ostracoda, Cypridina, Entomis, Kirkbya, and Moorea ; 4 Merosto- 

 mata (Eurypterida), Himantopterus, Slimonia, Stylomtrus, and 

 ParJca ; Xiphosura 1, NeolimuLus ; Phyllopoda 1, Dictyocaris ; Am- 

 phipoda 1 ?, Necrogammarus ; Crustacean remains, Astacoderma (14 

 species). 3 genera (Stylonurus, Cypridina, and ParJca) occur in 

 the Old Red Sandstone, but not in connected areas. 16 genera and 

 26 species are common to the Wenlock and whole of the Ludlow, thus 

 reducing the true Ludlow Crustacean fauna to 71 species instead of 97. 



Beyozoa. — Heteropora crassa, Ceriopora sulcata, and Ptilodictya 

 lanceolate, are the only 3 Ludlow Bryozoa. The first and last are 

 Wenlock also. They occur in the Lower Ludlow and Aymestry 

 Limestone of Worcestershire and Shropshire. Ceriopora sulcata 

 occurs in the Ludlow of Ireland. No species occurs in the Upper 

 Ludlow or Passage-beds, either in South or North Wales, West- 

 moreland, or Scotland. The nature of the Ludlow shales and mud- 

 stones doubtless was the cause why the Actinozoa, Hydrozoa, Echi- 

 nodermata (Crinoidea &c), and Bryozoa, all mostly dwellers in clear 

 water, are so sparingly developed and distributed through the Ludlow 

 rocks, the Aymestry Limestone being of little palaeontological value 

 owing to its lenticular disposition, mode of occurrence, and uncertain 

 continuity. 



Beachiopoda. — Although by no means a small fauna, the Ludlow 

 Brachiopoda numbering only 48 species and 13 genera are less 

 than half as numerous as those of the underlying Wenlock rocks. 

 41 of these 48 had lived in the Wenlock seas and passed to the 

 Ludlow ; therefore only 7 species are Ludlow proper ; and only 3 

 species passed to the Devonian — Atrypa reticularis, iStrophomena 



