UPPER LIAS: DORSETSHIRE. 255 
locally restricted, but it is not so generally defined in the Upper 
Lias, that the occurrence of two or three specimens would 
enable us to fix a chronological horizon ; nor are .Authorities suffi- 
ciently agreed on the definition of species to justify very dogmatic 
statements. Forms identified as A. radians, and which may be 
taken at any rate as closely allied, have been recorded from the 
lower beds of the Upper Lias of the Midland counties,* and A. 
aalensis is noted from the same beds in Yorkshire.! (See p. 199.) 
Mr. J. F. Walker, however, records A. toarccnsis from one of the 
Basement Beds at Shipton Long Lane, Bothenhampton, and A. 
slriatulus (which I have also obtained) from the uppermost Base- 
ment-limestone at North Allington.J (See p. 200.) He takes these 
species as affording evidence of the zone of A. jurensis in portions 
of the Basement Beds. Rhynchonella Bouchardi, which occurs in 
a lower layer at Shipton Long Lane, is characteristic of the lowest 
portion of the Upper Lias. 
The general tendency of the evidence obtained here and at 
Ilminster, points to the conclusion that the zone of A. communis 
is less conspicuously developed than it is in the Midland counties 
and further north, and that it may locally be confined to the 
Basement-portion of the Upper Lias. 
Somersetshire. 
The Upper Lias in the neighbourhood of Ilminster and Yeovil 
has been studied in much detail by Charles Moore. The lower 
beds are usually exposed in the quarries where the Marlstone is 
worked, but the higher and more clayey portion of the group is 
seldom exposed, though it may be traced beneath the sands at the 
base of the Inferior Oolite. 
Locally Moore found it convenient to make the. following 
divisions: 
r Ammonite Beds or Upper Cephalopoda Beds. 
Upper Lias --I Saurian and Fish Bed. 
I Leptsena Clays. 
These beds were exposed in a quarry at Strawberry Bank, on 
the north of Tlminster. 
The Lcptana Clays lie in immediate contact with the Marlstone, 
and consist of about 18 inches of green, yellow, and brown 
laminated clays, yielding Lept&na (Koninckella^ Bouchardi and 
L. Moorei at the base, and higher up Thecidium rusticum, Aluria 
unispinosa, Sjnriferina ilminstcrensis, and Zidlania liassica. 
Foraminifera and Ostracoda likewise occur, as well as Terebratula 
ylobulina, Rhynclwnellapyymaa, Ammonites, and occasional remains 
of Fishes and Saurians. 
The Saurian and Fish Bed consists of nodular yellow earthy 
limestone, usually blue hearted, and occurring in flat irregular 
elongated and lenticular masses, rarely more than five inches 
* Jiuld, Geol. Rutland, p. 79 ; Walford, Proc. Warwickshire Field Club, for 1878. 
f Tate and Blake, Yorkshire Lias, p. 303. 
1 Rep. Brit. Assoc. for 1890, p. 799. 
Proc. Somerset Arch, and Nat. Hist. Soc., vol. xiii. pp. 120, 132. 
