1 84 NOTES ON THE LIAS IN THE NEIGHBOTJfiHOOD OP EA.DSTOCK. 



Sp. rostrata is also usually considered to be from the M. Lias, it 

 seems certainly to be rare in the M. Lias of this district, but is 

 common in our L, Lias here. In a block off a wall near Welton, I 

 obtained the following fossils, viz. :— Sp. Walcotti, two specimens, 

 Sp. rostrata, five specimens, Ter. cornuta, one specimen, Rh. 

 variabilis, two specimens, with Lima tuberculata, punctata^ 

 pectinoides, Fecten sululatus, Grtjphea arcuata, Cardinia attenuata, 

 Listeri : the two species occurring in the same block with fossils 

 decidedly from the L. Lias. There is therefore no doubt about 

 Spiriferina rostrata and Ter. cornuta being found in the L. Lias — 

 the horizon being the upper part of the Bucklandi zone. 



Bed (i) graduates insensiblyinto the clay (h,) the top of the Lime- 

 stone containing the phosphatic nodules occasionally, which are so 

 characteristic of the basal part of the thick mass of clay. Higher 

 up the clay is blue grey, stiff and with few fossils. 



The bed (g) though thin is important. It has yielded Ammonites 

 which fix its position at once in the Liassic series. "We have 

 mentioned above that it represents the Obfusus-zone, — the proof 

 of this we obtained here. On one occasion we found a finely 

 weathered example of this species, on another we came upon 

 quite a nest of Ammonites, including A. ohtusus, six young 

 specimens, A. p>l(inicostatus about as many, and a fine specimen of 

 A. ziphus. "We notice that these three species occur together on 

 plate 406 of the '' Mineral Conchology." We have them again 

 together on a block which we obtained from Lyme Regis. 



Our specimen of A. %iphus, 3^ inches across, agrees so well 

 with the description of ^. Dudressieri, D'Orb. that we must 

 consider the latter name as merely a synonym. Quenstedt has 

 before remaked on their apparent identity (Jura. p. 97.) but 

 because the French type was supposed to be from the U. Lias (an 

 error, it has been shown) he feared ^to unite them. Another 

 example of that reasoning in a circle which is the bane of 

 geologists. Moreover the young whorls of this species are not to 

 be distinguished from A. planicostatus, so much so that Sowerby 

 in the letter-press to plate 406 considers them one species. 



I 



