On Cycloloculina. 539 



C. The secondary shell deposit between the perforations is 

 entirely wanting, and the test, consequently, never acquires the 

 coarse and weathered appearance which marks many specimens of 

 C. annul ata. 



D. The annular chambers vary in diameter and in sectional 

 shape. 



The genus being thus established, and its two distinctive species 

 having been determined by the examination of recurrent specimens, 

 we had reached a point at which it became imperative that some 

 organised effort should be made to determine the exact locality, if 

 not the precise geological stratum, from which this interesting 

 fossil is derived. We therefore made the following series of 

 gatherings of a strictly localised character, taking whenever 

 possible, not only a sample of the shore- sand, but of the rocks 

 and other deposits exposed at low spring tides, and of the sea-floor 

 by means of dredging. 



1. Shore-sand. From a small sand-bay, or pocket, in the 

 shelter of the spit of shingle that runs out to sea opposite Park 

 Farm, on the eastern side of the Bill. (It may be observed that 

 this is the only spot on the eastern shore which is not covered at 

 all states of the tide with a greater or lesser depth of shingle, 

 derived apparently from the raised beach or Coombe Eock.) 



2. Mud. A green plastic clay (? Tertiary) dredged in five 

 fathoms outside the Mixon Bocks. 



3. Rock detritus. The indurated and Pholas-hored Tertiary 

 clay. Pebbles, and small boulders, dredged in five fathoms outside 

 the Mixon Eocks, locally known as "The Clibs." 



4. Eock detritus. The Alvcolina limestone forming the Mixon 

 Eocks proper, of which most of the old houses in Selsey are built. 

 Dredged with Nos. 2 and 3. 



5. Eock detritus. The muddy sand found in the pools under 

 the boulders upon the highest point of the Mixon Eocks, piled 

 round the Mixon Beacon and uncovered at low tide. This consists 

 of the detritus of Nos. 2 and 3 mingled with recent Foraminifera. 



6. Shore-sand. From the commencement of the " sands " 

 opposite the Marine Hotel, extending slightly eastward towards 

 the extreme point, off which are the Mixon Eocks. 



7. Shore-sand. From the same point, extending about a 

 quarter of a mile westward, opposite " The Bungalows." 



8. Mud-deposit. Opposite Thorney (New) Coastguard Station, 

 called by Mr. C. Eeid the " Selsey Beds." A brown loamy 

 (Pleistocene) mud, with much detritus of derived fossil Mollusca. 



9. Mud-deposit. A Post-Tertiary estuarine clay, of deep 

 indigo blue colour, about three feet thick, separating No. 8 at this 

 point from No. 10. 



10. Bracklesham Beds. The Pholas-bored Eocene belt that 



