72 GASTEROPODA OF THE INFERIOR OOLITE. 



given in ' Judd's Geology of Rutland,' and more recently in another Survey Memoir 

 by Messrs. Jukes-Browne and Dalton. So extensive is this subject, that I may well 

 be excused for not entering into particulars in an " Introduction to the Inferior 

 Oolite Gasteropoda." As regards the position of the Lincolnshire Limestone in the 

 geological scale, it has generally been referred to the Soioerbyi- subzone. But I 

 am disposed to think that the greater portion of it belongs to the upper part of the 

 Murchisonce-zone. This would bring it on the level of the Oolite Marl of the 

 Cotteswolds, simply as regards geological time. I think that there can be little 

 doubt, from the abundance of Nerincea Gottesivoldice in the compact limestones of so 

 many localities, that such beds are on the horizon of the Oolite Marl, or just a 

 little below, whilst the abundance of casts of Natica cincta (Leckhamptonensis) seem 

 to point to the Oolite Marl itself. But it is apparently above these beds where 

 we find that finely oolitic and broken shell-rock which swarms — though only at rare 

 intervals — with Gasteropoda. Unfortunately they are much rolled, but now and 

 then some really good specimens are obtained. Though the prevailing forms are 

 decidedly small in these beds, yet some shells, especially those of Nerincea, attain a 

 considerable size. 



By far the richest exposure of this class of beds is at Great Weldon, four and 

 a half miles south-south-east of Rockingham, in Northamptonshire. As a section it 

 is of no value, being a mere roadside opening near the village, about 8 feet in depth. 

 The uppermost 4 feet consist of a shivery or platy kind of rock, with numerous 

 small Oysters on the bedding planes. The lower half is a comminuted shell and oolite 

 rock, and it is on the top of this that the richest accumulation of small Gasteropods 

 may be noticed. A few hundred weights of well selected stuff will afford employment 

 to the fossil hunter during many a winter's day. Innumerable small Gerithia of the 

 limceforma group, some of them identical with G. Beanii of the Yorkshire Beds, 

 are probably the most characteristic fossils. Monodonta laevigata, usually the typical 

 form, but rather smaller than Dundry specimens, is on every block, and small 

 species of Trochus, &c, are very numerous. The largest shells I have met with are 

 the so-called " Phasianellas," which seem to occupy the place of Natica, here almost 

 entirely unrepresented. The curious shell Cloughtonia cincta occurs here, and also 

 at Ponton, but is rare. This constitutes another link with the Yorkshire Beds. I 

 am not aware of its ever having been detected further south. 



Another exposure is at Wansford, about eight miles west of Peterborough. 

 This was more famous in former days, and is probably the locality " near Peter- 

 borough" of the Sharp collection. The Northampton collectors have obtained 

 some good things from here, but the section is for the most part grass grown, and 

 fine fossils are scarce. 



The next best place is the railway cutting at Great Ponton. The depth of the 

 cutting is about 20 feet. The beds which contain the Gasteropoda are very limited 



