48 GASTEROPODA OF THE INFERIOR OOLITE. 



considerable depth below the worked stone. The top of this series would be the 

 " solid block of bluish-grey limestone," on which the so-called Sauzei-hed reposes. 

 This Sauzei-hed is one of the most remarkable fossil-beds in Dorsetshire, and has 

 mixed relations, no doubt, both with the Lower and Upper Divisions of the 

 Inferior Oolite, though in drawing the line we must concede it to the Upper 

 Division. This is another case of a misnomer, as far as Frogden Quarry is 

 concerned, since it contains hardly any specimens of Sphceroceras Sauzei. Most 

 of the Ammonites are keeled, which at first sight would militate against its being 

 placed in the Upper Division. Again, what I conceive to be the "true Sowerbyi" 

 or something very near to it, is far from being uncommon in this bed. All we can 

 say, therefore, is that probably somewhere or other Sphceroceras Sauzei does 

 characterise a bed which is about the same horizon, and contains a somewhat 

 similar facies to this one. 



The Gasteropoda in the Sauzei-hed are abundant and well preserved, and the 

 matrix is on the whole favorable for extraction, being a soft, whitish limestone 

 with green (? glauconitic) grains passing into the ironshot Oolite of the bed above. 

 For the sake of distinction, and as indicating the position assigned to it, I call this 

 bed Hp The Gasteropoda seem to present forms that are intermediate between 

 the " Sowerbyi-hed " of Bradford Abbas and the more recognised species of the 

 Humphriesianus -zone. It is very rich in Pleurotomarice, another characteristic 

 which it shares with the beds of Bayeux ; in some other respects it seems to possess 

 features of its own. 



At Milborne Wick the Sauzei-hed (Hj) seems more or less blended with the 

 main Humphriesianus-hed (H 3 ), nor do I know of the distinctive development of 

 this sub-stage anywhere else throughout the country. 



The main mass of the Humphriesianus-zone (H 3 ) calls for few remarks. It is 

 not particularly rich in Gasteropoda as far as my experience goes. Probably some 

 of the specimens from H : in an ironshot matrix ought rather to be referred here. 



The remaining sub-stage of the Humphriesianus-zone (H 3 ) deserves a little atten- 

 tion on our part. It is a thin bed of brown ironshot Oolite, mostly of a peculiar 

 character, which lies just above a bed very full of Terebratula sph&roidalis. There 

 is a most curious admixture of Ammonites. Am. Martinsii is common high up, 

 and several species of Cosmoceras and Oppelia abound. Gosmoceras Niortensis and 

 allied forms are especially numerous, and there occurs the curious little Am. 

 cadomensis, which may well give its name to the bed, simply as a local name. 

 Probably neither Am. Humphriesianus, nor Am. Parhinsoni properly so called occurs 

 here, and it is evidently debateable ground between the two zones. It contains 

 numerous species of Astarte, and many Gasteropoda. This horizon, or sub-stage, 

 cannot be very far from that of P x at Burton Bradstock. However, this must be 

 lower in the geological scale, though not much. The Gasteropoda occur for the 



