112 



STRATIGRAPHICAL GEOLOGY 



Crustacea. Ogygia Selwyni, O. marginata, Mglina, binodosa, M. 



caliginosa, Calymene parvifrons, Caryocaris Wrighti. 

 Bradiiopoda. Lingula petalon, Monobolina plumbea, Orthis alata. 



Lamellibranchia. Redonia anglica, Palsearca amygdalus. 

 Gastropoda. Hyolithes (Theca) vaginula. 



Cephalopoda. Orthoceras sericeum. 



Fossils of the Llanvirn Series 



Hydrozoa. Didymograptus bifidus, Did. Murchisoni, Did. nanus, 



Did. acutidens, Diplograptus (Amplexograptus) 

 confertus, Diplograptus calcaratus, Glossograptus 

 ciliatus. 



Trilobita. Ampyx nudus, Illsenus Hughesi, Placoparia cam- 



brensis, Phacops llanvirnensis, Barrandea Homfrayi. 



Bradiiopoda. Lingula attenuata. 



Fig. 25. GROUP OF ARENIG FOSSILS. 



a. Ogygia Selwyni. 

 6. CEglina binodosa. 



c. Palsearca amygdalus. 



d. Euoinphalus corndensis. 



Gastropoda. Euomphalus corndensis, Pleurotomaria llanvirnensis, 



Conularia llanvirnensis, Bellerophon perturbatus. 

 Cephalopoda. Conoceras llanvirnense, Orthoceras caeresiense. 



Fossils of the Llandilo Series 



Radiolaria. Species of Styptosphaera, Spongoplegma, Diploplegnia, 



Stauroplegma, Haliomma, Dorysphaera, Doryplegma, 

 Triplosphaera. 



Foraminifera. Saccammiua Carteri. 



Hydrozoa. Didymograptus superstes, Diplograptus foliaceus, Dicel- 



lograptus divaricatus, and D. sextans, Nemagraptus 

 (Coenograptus) gracilis, Dicranograptus ramosus. 



Crustacea. Asaphus tyrannus, Ogygia Buchi, Ampyx nudus, Tri- 



nucleus fimbriatus, Agnostus M'Coyi, Acidaspis 

 Jamesi. 



Brachiopoda. Lingula brevis, Orthis alata, 0. confinis, Siphonotreta 

 micula (ranges into Bala). 



Gastropoda. Maclurea Logani, M. magna, Ophileta compacta, Bellero- 



phon perturbatus (passes to Bala). 



Cephalopoda. Orthoceras Avelinei. 



