214 PROCEEDINGS OF THE COTTESWOLD CLUB 



connections between the several chambers, being, in fact, 

 perfect pseudomorphs of the animals which formed and in- 

 habited them. Again, scarcely a piece of flint can be taken 

 wdiich does not contain Zanthidia. In some specimens they 

 are extremely numerous. The Zanthidia are said to be the 

 sporangia of the Desmidiaceae. Some 5 or 6 different 

 forms occur in flint. Some flints also contain immense 

 numbers of globular bodies which have been erroneously 

 called Pyxidicitla ; they do not however belong to the 

 Diatomaceae, and it is far from certain what they really are : 

 possibly they are sponge gcmmules. I have in my 

 cabinet a section of flint which is literally crowded with 

 them. 



Chalcedony is frequently found on the inside of hollow 

 spongeous flints, sections of which are lovely objects for 

 the polariscope. 



Polycistina are occasionally found in the chalk, but it 

 has never been my fortune to meet with any. 



The ordinary fossils of the chalk, such as the Brachio- 

 poda, Conchifera, and Echinoidea, are not exactly micro- 

 scopic objects ; but sections of the tests, especially 

 those of the Brachiopods, are very interesting ; and so 

 are sections of the plates and spines of Echinoderms. 

 Fragments of bones which are occasionally found in the 

 Chalk should also be submitted to microscopical examina- 

 tion, as by this means it may be determined whether the 

 bone under examination belongs to the Mammalia, Aves, 

 or Reptiha ; and the microscope may also be applied 

 to fragments of wood which are occasionally met with. 



Echinodermata are plentifully represented in the chalk 

 by the Echinidea or sea-urchins, and the Asteridea or star- 

 fishes ; but hitherto no remains of the Holothuria, or 

 sea-slugs, have been recorded. Upon examining some 

 washed chalk some time since, which I obtained at 

 Caterham Junction, I w^as considerably delighted to find 



