ZONE OF AMMONITES ANGULATUS. 



G3 



crowded with Ammonites planorbis, known at Scarborough and Whitby as Am. eriigaius. 

 Bean. 



The Coral-bed at Lussay, Isle of Skye,^ probably represents the zone Am. planorhiH, 

 as I found the same species as the Ilcbridcan coral in the Hght-coloured clays with 

 Am. plauorbis at Street. 



This lowest Ammonite-zone has, therefore, a wide geographical distribution throughout 

 the Lower Lias of the northern, midland, and southern counties of England, and it 

 retains the same relative position in the Lower Lias of France, Germany, and Switzerland. 



Fossils of the Ammonites planorbis beds. — The fauna of this zone is very limited; at 

 present I know only the following species : 



Ichthyosaurus intermedius, Comjb. 



— tenuirostris, Conyb. 



— communis, Conyb. 

 Plesiosaurus Hawkinsii, Conyb. 



— Etheridgii, Huxl. 



— rugosus, Ow. 



— dolichodeirus, Conyb. 



— megacephalus, Stutch. 

 Dapedius. 



Pholidophorus leptocephahis, Ag. 



— Strickland!, Ag. 

 Ammonites planorbis, Sow. 



— Johnstoni, Sow. 

 Lima punctata, Sow. 



Lima gigantea, Sow. 



— pectinoides, Sow, 

 Cardinia crassiuscula. Sow. 

 Unicardium cardioides, Phil. 

 Ostrea liassica, Strick. 

 Mjacites musculoides 1 Schloth. 

 Rhynchonella variabilis, Schloth. 

 Cidaris Edwardsii, fJ'^r. 

 Pseudodiadema lobatum, Wr. 

 Hemipedina Bechei, Brod. 



— Bowerbankii, Wr. 



— Tomesii, Wr. 

 Isastraea Murchisoni, Wr. 



2. The Zone of Ammonites Angulatus. 



Synonyms. — " Sandige Kalke und Sandsteine xmi Am. angulatus, Quenst.," 'Flotzgeb./ 

 541. " Gres infraliasique fpars)," Dufrenoy and De Beaumont. " Gres liasique, gres de 

 Hettange," Terquem, ' Paleont. du Dep. de la Moselle,' p. IL "Die Schichten des Am- 

 monites angulatus" Oppel, ' Juraformation,' p. 28. " Zone 'k Ammonites Moreanus^' Martin, 

 "Pal. Stratigraph. de I'lnfra-lias du Depart, de la Cote-d'Or,'' ' Mem. Geol. Soc. de 

 France,' p. 38, 2nd serie, 1860. 



The zone of Ammonites angulatus, so far as it has been exposed, appears to be 

 imperfectly developed in the British Isles, and from the difficulty experienced in separating 

 its beds from the Bucklandi series, they were grouped with the latter in ray memoir. 

 On the Continent, however, and especially in Fi'ance, this zone forms a very important 

 horizon, and contains a rich fauna. M. Jules Martin,^ in his valuable memoir on the 

 Infra-Lias of the department of the Cote-d'Or, says, " this zone forms one of the best 



1 'Quart. Journ. Geol. Soc.,' vol. xiv, pp. 4 and 34. 



2 ' Paleontologie Stratigraphique d'Infra-Lias du departement de la Cote-d'Or," p. 39, 1 860. ' Mem. 

 Soc. Geol. de France,' 2nd serie, tom. vii, Mem. No. 1. 



