L870.) TATE—GLOUCESTERSHIRE LIAS. 395 
That the zone of Ammonites capricornus is intimately connected 
with the Marlstone there cannot be a doubt, and in the Yorkshire 
Lias it has for many years been grouped with it; but as the zones of 
Ammonites Jamesont and A. ibex, in this country, have usually been 
regarded as imperfectly fossiliferous, the necessary data for compari- 
son being absent, the position of these zones in the Middle Lias has, 
with some degree of reasonableness, been questioned, more especially 
because the lithological conditions of the upper zones of the Lower 
Lias (sens stricto) are repeated in the zone of Ammonites Jamesont. 
Professor Ramsay, in his Anniversary Address to the Geological 
Society in 1864, leads us to infer that the divisional line between 
the Lower and Middle Lias is one of convenience; he shows by 
tables the number of species which pass upwards through the zones 
of the Lias, andin a résumé states that from the zone of Ammonites 
raricostatus, Which forms the top of the Lower Lias, six species 
(eighteen species only are recorded), or about thirty-three per cent., 
pass upwards into the Middle Lias, whilst from the zone of Ammo- 
nites Davee (here equivalent to the zones of A. Jamesoni, A. rhex, 
and A. capricornus) thirty-one species pass upwards, or very nearly 
thirty-eight per cent. The facts from which the above results have 
been obtained, if examined in detail, show that, as regards the species 
of Ammonites, their range is trenchant, but that common species of 
fossils graduate upwards from one division to another. 
The number of species recorded in England from the several zones 
is given as follows:—zone of A. owynotus, 6; A. raricostatus, 18 ; 
A. Henley and A. Davei, 82; and considering the paucity of fossils 
from these zones bordering on the junction of the Middle and Lower 
Lias, it would be unphilosophical to lay too much stress upon their 
palzontological affinities and differences. 
The scanty published information we possess relative to the 
organic remains of the lowermost zone of the Middle Lias is given 
by Oppel and Wright. The former author estimates the thickness 
of the zone of Ammonites Jamesoni in Robin Hood’s Bay at 100 feet, 
and mentions the following fossil species :—Ammonites Jamesoni, A. 
Taylor, Belemnites elongatus, Gryphea obliqua, Pholadomya decorata, 
and Pinna folium. He also notices the development of this zone at 
Charmouth, but gives no list of fossils; Mr. C. H. Day, however, has 
enumerated twenty-eight species of Mollusca from it. In the neigh- 
bourhood of Cheltenham, Dr. Oppel did not determine the occurrence 
of the zone of Ammonites Jamesoni; but Dr. Wright says* ‘in Glou- 
cestershire the beds representing this zone are found only in some deep 
brick-pits near Leckhampton, whence I obtained fragments of Ammo- 
mites Jamesoni and Gryphoea obliqua, with Rhynchonella vimosa.” 
Having during a series of years made a comparatively extensive 
collection of fossils from the “‘ Belemnite beds” of the neighbourhood: 
of Cheltenham, and being aided by several collectors and other 
sources of information, I am enabled to record from the zones of Am- 
monites oxynotus and A. raricostatus fifty species, and from the zone 
of Ammonites Jamesoni one hundred and sixteen species; these data 
* Mon, Brit. Asteriadx, Pal. Soc. p. 78 Soa a 
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