484 



FOSSILS OF LOWER LUDLOW. 



[Ch. XXVIl 



ri». 5T5. 



Fig. 576. 



Atrypa reticularis, JAxm. {Terebratula affinis, Min. Con.) Aymestry. 

 a. Upper valve. b. Lower valve, 



c. Anterior margin of the valves. 



The Aymestry Limestone contains so many shells, corals, and trilobites 

 agreeing specifically with those of the subjacent Wenlock hmestone, that 

 it is scarcely distinguishable from it by its fossils alone. Nevertheless, 

 many of the organic remains are common to 

 the Aymestry limestone and the Upper Lud- 

 low, and several of these are not found in the 

 Wenlock.^ 



8. Lower Ludlow shale. — This mass is a 

 dark gray argillaceous deposit, containing, 

 among other fossils, many large chambered 

 shells of genera scarcely known in newer 

 rocks, as the Phragmoceras of Broderip, and 

 the Lituites of Breyn (see figs. 576, 57*7). 

 The latter is partly straight and partly con- 

 voluted, nearly as in Spirula. 

 rhragi7ioceras 'veniricosnm, J. Sow, The Ortlioceras Ludense (fig. 578), as 



( Orthoceras ventricofium, St«in.) -.^ ,, i i i i , a* i • 



Aymestry ; i Lat. size. Well as the cephalopod last mentioned, is 



Fig. 577. 



peculiar to this member of the series. 



Fig. 5TS. 



Litmte'i giffanietis, J Sow. 

 Near Ludlow; al&o m the Avmestry 

 and W <?n;ocL limestones ; ^ nst. size. 



Fragment of Orthoceras Ltidense, J. Sow. 

 Lcintwardine, Shropshire. 



A species of Graptolite, G. Ludensis, Murch. (fig. 588, p. 437), a form 

 of zoophyte which has not yet been met with in strata above the Silurian, 

 Dccurs plentifully in the Lower Ludlow. 



* Murchison's Siluria, p. 133. 



