208 



I. — Zone of Ammonites macrocepliahis. Beneath the Kelloway 

 Rock, in Wiltshire, there is a bed of dark blue clay containing 

 many Ammonites and argillaceous nodules, having chiefly 

 yovmg Ammonites and other molluscs for their nuclei; this 

 bed was well exposed in the railway cutting near Trowbridge, 

 and I fortunately possess a very complete suite of the fossils 

 collected therefrom. The clay was especially rich in Cephalopoda, 

 as the following Hst shews : — 



Cephalopoda. 



Ammonites macroceplialus, Schlotli. Amm.omtes Goweiianus, Sow. 

 II modiolaiis, Uhwyd, " Konigii, Sow. 



II Chamusseti, d'Orh, Belemnites abbreviatus, Mill. 



CONCHIPEKA. 



Trigonia clavelluta, Sow. Modiola bipartita, So^o. 



Avicula expansa, Phil. Nucula PhiUipsii, Mor. 



On the Yorkshire coast the Kelloway rock is largely 

 developed and separated from the Cornbrash by a bed of 

 dark-bluish clay, more or less laminated, varying in thickness 

 from four inches to six feet : this, the so-called " clay of the 

 Cornbrash," appears to represent the zone of Am. macrocephalios, 

 as it contains several species of shells which are rarely, if ever, 

 met with in the Cornbrash, as Ammonites macrocephahis, Schloth., 

 Sanguinolar ia parvula, Bean., Cardium latum, Bean., Opis 

 triangularis, Bean., Belemnitis tomaiilis, Phil.* The claws and 

 carapaces of two Crustacea, Glyphoea rostrata, Phil., G. Birdii, 

 Bean., occur in round argillaceous nodules in this clay at 

 Cayton Bay, with Hemipedina Woodwardii, Wr., collected 

 therefrom, and given to me by the late Dr. Murray. 



* Sangninolaria parvula and Cardium latum: — These very doubtful species, 

 founded on solitaiy examples, are really unworthy of being continued in any 

 list of Cornbi'ash fossils. The fiist is no true Sanguinolai-ia. Opis triangularis. 

 Bean, is hardly even a variety of Isocardia nilida, Phillips ; it is not an Opis ; 

 and I have struck it out of my list of Cornbrash fossils. Ammonites niacrocephalus, 

 Schloth., is not peculiar to the clay, but is found much more abundantly in the 

 true Co]-nbrash below. Tlie only cbaructeristic fossil, therefore, is the species 

 referred to, Belemnites iorncdilis, PMllips; but I cannot refer it to any of the 

 varieties of B. Oweni ia which Prof. Phillips now includes B. iornatilis — it comes 

 nearer to .B. abbreviatus. Note by J. Lbckenbt, Esq. 



