240 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Nov. 18, 



4. Paludina ? Ovato-conical ; the volutions very rounded, and 

 covered with spiral striae, which sometimes appear larger and 

 smaller alternately, and are crossed by distinct lines of growth. 

 (PL XIII. fig. 8.) Frequent. 



This shell looks as much like Cyclostoma as any of the spirally- 

 threaded Paludince known to me. The spiral threads are, in some 

 specimens, more prominent about the middle of the volution. 



There is a colour-band on one of my spiral shells ; but I cannot 

 determine the species. 



On this list (which omits only some forms too imperfect for notice) 

 it may be remarked, — 1. That very few more organic forms are to be 

 expected from the western side of Shotover, the part as yet chief! v 

 examined ; for the specimens include perhaps only two or three not 

 found by Jelly and mentioned by Strickland and Fitton. 2. That 

 none of the marine forms usual in Lower Greensand occur in it. 

 3. That, while the general analogy is to estuarine and freshwater 

 species, and while some of the species seem to be either the same 

 or very nearly the same as known Mid- Weal den types, there are 

 characters in some of the spiral shells worthy of remark, as tending 

 perhaps towards Littorina as much as to Paludina. 



Admitting, on the evidence which has been adduced, that the 

 Iron-sands of Shotover, nearly to the top, were accumulated under 

 the influence of river-currents, which scattered the remains of fresh- 

 water organic life among them, we find this conclusion strengthened 

 by the facts, that at Combe Wood, a little farther to the south-east of 

 Shotover, these sands cover a Purbeck deposit, — "Malm," with 

 Paludina elongata and another species, Planorbisl, two species of 

 Mytilus, Modiola, and Cypris. Below is the Portland-rock. 



Similar facts occur at Garsington, near Oxford, and at Stone and 

 Whitchurch in Buckinghamshire. 



The sands on the Hill of Stone, near Aylesbury, are principally of 

 the same type as those of Shotover ; they rest on Purbeck clays, and 

 "Malm" or "Retch," which cover the Portland. Thus the Iron-sand 

 of Shotover is connected with the more extensive deposits of Buck- 

 inghamshire and Bedfordshire ; and the ancient generalization of 

 Holloway, who united in one deposit the sands, ochres, and fuller' s- 

 earth of Woburn and Shotover, is confirmed. 



Smith, who regarded these sands as of the same great group as 

 the Hastings Sands — in this agreeing with Conybeare — records the 

 occurrence, at Steppingley Park, near Woburn, of Gault over the 

 sands, and containing its characteristic Ammonites. Thus we find 

 the " Iron Sands " to be inferior to Gault, and superior to Purbeck 

 beds ; they may at present, with much probability, be referred to the 

 Hastings Sands ; it is, however, possible that they may be an estuarine 

 deposit of the Lower Greensand age. Gault with characteristic 

 Ammonites, Belemnites, Nuculce, &c, occurs at Culham, a few miles 

 south-west of Shotover. It is there separated by only eight feet of 

 Greensand (whose geological data are not yet certainly determined) 



