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, 

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

 mense quantity of corals and crinoidea, — the BeUerophon ienuifas- 

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

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

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

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

 Terebratula cuneata, Dalm., the Producta depressa, 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 Lingula, and a new species of Orthis ; also the Cyrtia tra- 

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

 Orthocera annulata. Sow., besides Crinoidea, &ic. Mr. Murchi- 

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



" Mr. Murchison's third formation includes the Horderley 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 Icevis, Sow., the P. 

 oblongus, Murch., a new species of Leptana one o[ 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, 

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

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

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

 form the fourth formation of the serics.f 



♦ Mr. Murchison now names this second forniation the Wenlock Limestone. 

 t Mr. Murchison now names the third formation simpl}' Cardoc timestune from 

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



