By the Ven. Archdeacon Macdonald. 157 



of the family of the Coronarii so abundant in the Middle Oolites/' 

 Mr. Sharpe paid Wiltshire the compliment of naming a remark- 

 able, though small species, found on Morgan's Hill, Ammonites 



Wiltoniensis. It is the only known 

 specimen. 1 There are also some 

 fossiliferous beds in the Lower 

 Chalk or Chalk Marl, as for ex- 

 ample on Canning's Hill on the 

 London road, and it may be re- 

 Ammonites wiltoniensis (sharped marked that many of the forms 

 which exist in the Upper Green Sand are continued into these beds 

 of the Chalk, though they cease to exist soon after the commence- 

 ment of that stratum. The sponges occur very rarely in the Chalk 

 itself, although so abundant in the flints. The Devizes collections 

 are rich in these remains. 



The Upper Green Sand follows the outline of the Chalk hills, 

 forming terraces round their bases, and throwing out picturesque 

 promontories into the surrounding vallies. It is to these slopes, 

 clothed as they usually are with luxuriant timber, that much of 

 I the beauty of the scenery around Devizes and Roundway is due. 

 The greatest depth of the Upper Green Sand in this parish is about 

 140 ft. It is very silicious towards the top, and mostly consists 

 of a greenish quartzose sand, but the greater portion of the stratum 

 is a fine sand with grains of mica. Towards the bottom, as it ap- 

 proaches the Gault, it is very argillaceous, and gradually passes 

 into a heavy blue clay. With the exception of certain layers or 

 blocks of rough sandstone, which occur about the middle of the 

 stratum, the Upper Green Sand of North Wilts yields no stone 

 capable of being used as a building material. The sandstone is 

 composed of sand united by a calcareous cement, probably derived 

 i from the decomposition of the shells which it contains, and of these 

 'there is sometimes a great abundance. 



I The fossils of the Upper Green Sand are usually found in the 

 |3ondition of casts only, but these are so sharp that all the charac- 

 teristic lines and markings are preserved, and the species are easily 



1 The fossils mentioned above are in the collection of Mr. Cunnington. 



