234 OUR COMMON BRITISH FOSSILS. 



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

 the narrow circle of the present British seas. 



Tcrebratulida 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 Australis 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. ziG.Terebratula biplicata (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 Terebratula occur in the limestone of all the geolo- 

 gical periods ! Terebratula 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 



