"Vol. 54.] LIMESTONE OF THE COUNTRY AROUND LLANDUDNO. 393 



List of Fossils {continued). 



o 



o 



CO ^ 



15 



® a 





O 



a, 

 a, 

 P 



Streptorhynchus crenistria, Phill 



Terebratula gillingensis, Dav 



„ hastata, Sow , 



Fenestella plebeia, M'Coy 



Bhabdomeso7i gracile, Phill 



Bairdia plebeia, Reuss 



CythereUa aqualis, J. & K 



Griffithides seminiferus, Phill , . . . 



Leper ditia Okeni, Miinst , 



Serpulites carbonarius, M'Ooy , 



Alveolites septosa, Flem 



Chcetetes tumidus, Phill 



Cyathophyllum Stutchburyi, M.-Edw. 

 Lithostrotion irregulare, M'Ooy , 



, , Martini, M. -Ed w 



,, M'Coyanum, M.-Edw. ... 



„ Portlocki, M.-Edw. 



Lonsdaleia duplicata. Mart 



Syringopora geniculata, Phill 



„ ramulosa, Goldf 



Zaphrentis Enniskilleni, M.-Edw. & H 



Endothyra amnnonoides, Brady 



,, Bowmani, Phill 



Nodosinella sp 



O 



O. 



o. 



R. 

 R. 



R. 



R. 



R. 

 O. 

 O. 

 O. 

 O. 

 O. 



0. 



Nearly all the commou and very common species found in the Middle White 

 Limestone occur in the Upper Grey Limestone, and as with few exceptions they 

 are from near the base of the subdivision, there is a difference in the horizon of 

 500 feet. Most of those at Great Orme's Head were found in the black shale 

 at the base, and it seems that the occurrence of particular species depends more 

 on the lithological character of the beds than on the horizon at which they 

 occur. The relative number in which each species occurs refers to the Llan- 

 dudno area alone. 



south-east, while that of the southern dips north-west towards the 

 intervening valley of Crenddyn, coloured as Millstone Grit on the 

 Geological Survey map. As the valley is a synclinal 2 miles loDg 

 and nearly a mile wide, the Upper Grey Limestone might be expected 

 to occur in it, but that subdivision has not been found. 



South-east of Eglwys Rhos there is a very confined area of 

 red and yellow sandstone about Bod-y-Sgallen, resembling the 

 Purple Sandstone of the Vale of Clwyd, though partly coloured as 

 limestone and partly as Millstone Grit on the Geological Survey 



