I860.] WEIGHT LIAS AND BONE-BED. 331 



Pecten Ycdoniensis is found in blocks on the shore, and likewise 

 slabs of sandstone with Pullastra arenicoia. The Bone-bed abounds 

 with the teeth of Ceratodus and other Fishes ; and the vertebrae and 

 other bones of Saurians and Fishes are strewed, together with Copro- 

 lites, abundantly throughout this remarkable rock, which here forms 

 a conglomerate composed of rounded portions of an argillo-arenaceous 

 and calcareous rock, with which are mingled the bones, teeth, and 

 coprolites of Ecptiles and Fishes. 



Tho Bristol Museum contains a series of fossils from the Aust 

 Bone-bed; but the finest collection of Ceratodus teeth from this 

 locality has been made by Mr. Higgins of Birkenhead, who reckons 

 that he has found 140 different forms of the teeth of this singular 

 genus. 



Section at Penarth Cliff. — On the opposite side of the Bristol 

 Channel at Penarth Head, near Cardiff, a magnificent section is 

 exposed, showing the Lower Lias and Avicida contorta beds resting on 

 the variously coloured marls of the Keuper. The lower half of this 

 cliff may bo considered as a roll of the same beds which I have 

 already described as occurring at Garden Cliff, 44 miles higher up the 

 Birer Severn. At Penarth the relative position of the zone of the 

 Ammonites Bucldaadi, the zone of Ammonites planorbis, and the zone 

 of Avicida contorta, with the red and grey marls of the Keuper, are 

 all seen in situ in this fine and instructive coast-section. 



The upper part of Penarth Head is composed of alternate beds of 

 limestone and shale which represent the zone of Ammonites Twrm ri, 

 with Pentacrmus tuberculatum, Mill., Cardmia ovalis, Stutch., and 

 Qryphoea incurva, Sow. These attain a thickness of from 10 to 

 15 feet, and overlie the Lima-beds or zone of Ammonites BucJclandi, 

 which, in like manner, consists of alternate beds of limestone and 

 shales, baring a thickness of 50 or 60 feet. They are well seen 

 in tho cliff, forming a vertical wall, and may be examined in the 

 quarries behind the church. I collected hei'c Lima antiqua, Sow., 

 Lima gigantea, Sow., Lima punctata, Sow., Lima pectinoides, Sow., 

 Cardmia hybrida, Stutch., Unicardiiim cardioides, Phil., two or three 

 species of Pecten, and a large-ribbed Limn. Beneath the Lima- 

 scries are beds of laminated clay, containing Ammonites planorbis, 

 Sow., and alternate beds of marly clay and courses of limestone, with 

 an abundance of Ostrea liassica, BtrickL, on the surface of some of the 

 slabs. These beds attain a thickness of aboul 1" Peel or more, and 

 are underlain by a bed of stiff clay containing Ostrea Kassica and 



Modiolo minima. 



The Avicula contorta beds form an important feature in the cliff, 

 consisting, as they do, ot'hlackish Bhales interposed between the light- 

 coloured marls of the Keuper, helow. and the light-Coloured lime- 

 stones and shales of the j. planorbis bed above. By measurenu nt I 

 found the thicknee of the Avicida contorta series to be 18 feel i and I 

 could see them distinctly in the Beotion Borne miles "in in the channel. 

 The uppermost bed consists of 5 or 6 feel of a dark marly clay, with 

 Myacites and Area, of undescribed species, which lie in Beams; in 



