234 OUR COMMON BRITISH FOSSILS. 



geologist to " break ground " on, to be found within 

 the narrow circle of the present British seas. 



TerebrattdidcB is a well-known group of fossil 

 Brachiopods, which have been in existence from the 

 Devonian period without losing their distinctive cha- 

 racters up to the present day. The genus reached its 

 climax during the Oolitic period, when nearly seventy 

 species were in existence. Waldheimia Attstralis — the 

 antipodal representative — seems to be doing well 

 and flourishing yet, as though the country which 

 is still the abode of Marsupials (the low-pressure 



Fig. 216. — Terehratula bij>licata (Oolite). 



Secondary type of Mammalian life that preceded the 

 high-pressure forms of the Tertiary and Recent 

 periods) were a belated geological area both as 

 regards sea and land. What an abundance of species 

 of Terehratula occur in the limestone of all the geolo- 

 gical periods ! Terehratula hastata swarms in many 

 localities in the Carboniferous limestone. About 

 Castleton, Derbyshire, and near Clitheroe, Lanca- 

 shire, we get it in every stage of growth, and with 

 remnants of its ancient radiating colour-bands still 



