30 GASTEROPODA OF THE INFERIOR OOLITE. 
unfavorable to its development, and partly because the mechanical sediments mask 
those of organic origin. I have before observed that the horizon may be roughly 
represented as the zone of Am. radians. The lower portions (not visible in 
this section) may probably be the equivalents in time of the /Jwrensis-beds, as 
identified by Tate and Blake in Yorkshire, whilst the upper portion may be taken 
to represent the cynocephala-stage of Lycett. 
It so happens that in one place a complete section of the Inferior Oolite Lime- 
stone has slipped to the base of the cliff, and therefore we are fortunately able to 
effect an examination which would otherwise require a considerable, not to say 
dangerous, exertion. The following profile, therefore, though measured at the 
bottom, really represents the top of the cliff. Itshows us the Inferior Oolite in a 
nutshell, and affords a clue to its development in this neighbourhood and to a 
certain extent throughout the Dorsetshire district. Its modest dimensions seem 
puny in comparison with the bulky Cotteswolds and the still thicker masses 
of the Yorkshire Oolites. Nevertheless, though small it is regular in sequence 
and the life-zones are fairly shown, better perhaps than in any one section 
of the Inferior Oolite throughout England. Doubtless there are deficiencies, and 
the Parkinsoni-zone is in preponderating force. 
Profile No. 1, see page 31.—Taking these beds in ascending order and without 
too detailed a scrutiny, we perceive that above the main mass of “ Yeovil Sands” 
there occur about seven feet of sand-rock and calciferous grits between two lines 
of very thin, smooth, sharply-keeled Ammonites. These, no doubt, are the beds 
referred to by Oppel, who says that he found here the beds of Am. torulosus in 
the form of sandy, light grey limestone charged with numerous organic remains, 
amongst which he collected Am. torulosus, opalinus, and subinsignis, Turbo sub- 
duplicatus, Terebratula anglica, and Rhynchonella cynocephala.' 
Speaking from my own experience the fossils of this horizon are mainly confined 
to the vicinity of the upper line of Am. opalinus, which Oppel regards possibly as 
the equivalent of his zone of Trigonia navis. There is here a fossiliferous zone 
which teems with Am. opalinus, and I possess both the other species of Ammonites _ 
mentioned by Oppel from this place and most probably from the same horizon. 
Rhynch. cynocephala was also noted from here, and lkewise a few species of 
Gasteropoda, but not enough to constitute what the local collectors call a 
*‘Univalve Bed.” 
The remainder of the section upwards consists of five blocks of limestone, 
which measure altogether about twelve feet in height. The most notable shell- 
bed in the lower portion is one in connection with the ‘‘irony nodule” bed, 
a well-marked physical horizon in this neighbourhood. Ammonites greatly 
resembling Am. Murchisone occur hereabouts, and there are a sufficient number of 
" See Oppel, ‘Juraformation,’ p. 328, 1856-58. 
