50 Fossil Fishes. 



" The second formation, arising from the division of the greywacke 

 group, is composed of the Wenlock and the Dudley rock, which 

 swarm, so to speak, with corals, shells, and Trilobites.* Mr. Mur- 

 chison, divides it into two subdivisions : the upper comprehends the 

 Wenlock and Dudley limestone, which is a subcrystalline limestone, 

 highly concretionary, of a grey or blue color. It contains an im- 

 mense quantity of corals and crinoidea, — the Bellerophon tenuifas- 

 cia, Sow., the Euomphalus rugosus and discors, Sow., the Conularia 

 quadrisulcata, Sow., a new species of Pcntamerus, also of the Na- 

 tica, the Natica spirata, Sow., the Leptama euglypha, Dalm., the 

 Spirifer lineatus, Sow., and a new species of this last genus, the 

 TerebratuJa cuneata, Dalm., the Producta dcpressa, Sow., many 

 species of Orthocera, the Asaphus caudatus, Brong., the Calymene 

 Blumenbachii, Brong., and other trilobites. This subdivision pre- 

 vails remarkably in the neighborhood of Wenlock, in Shropshire, in 

 Caermarthenshire, at Dudley, and in Gloucestershire. The second 

 subdivision comprehends the Wenlock and Dudley argillaceous shales, 

 which are of a dark grey color, rarely micaceous, and contain nodules 

 of earthy limestone. In these strata are especially found a variety 

 of the Asaphus caudatus, the Calymene Blumenbachii, a new spe- 

 cies of LinguJa, and a new species of Or this ; also the Cyrtia tra- 

 pezoidalis, Dalm., a new species of Delthyris, an Orthocera, 

 Orthocera annulata, Sow., besides Crinoidea, &:c. Mr. Mui 

 son has never found the least trace of fishes in this formation. 



the 



" Mr. Murchison's 



Horderlev and 



May-hill rocks, which descend as far as the Black Rocks of Llan- 

 deilo and Builth. It is entirely devoid of the debris of fishes, and 

 is especially characterized by the Pentamerus Itevis, Sow., the P. 

 oblongus, Murch., a new species of Leptama one of Pileopsis, a new 

 terebratula, many crinoidea, some corals, undescribed species of tri- 

 lobites including the genus Cryptolithus, which have been discover- 

 ed in North America, and fourteen species of the genus Orthis dif- 

 ferent from those which have been found in the overlying formations, 

 including the Orthis Callacis of Dalm., and his O. Aperturatus. 

 The Asaphus Buchii, Brong., his genus Agnostics, and other un- 

 described s pecies, characterize the Llandeilo and Builth rocks, which 

 form the fourth formation of the serics.j 



* Mr. Murchiscn now names this second formation the Wenlock Limestone. 

 t Mr. Mi chison now names the third formation simply Cardoc limestone from 

 Caer Cardoc, where it is well seen, and the fourth simply Llandeilo formation. 



