THE AGE OF INVERTEBRATES OF THE SEA. r.g 



could not conscientiously affirm that the Brachiopoda, as far as 

 J am at present ac(iuainted with them, would be of much ser- 

 vice in proving it. The subject is worthy of the continued 

 and sekious attention of every well informed man of science. 

 The sublime Creator of the universe has bestowed 6n him a 

 thinking mind ; therefore all that can be discovered is legitimate. 

 Science has this advantage, that it is continually on the advance, 



],',f;. 6i.— Clrouj) of Older i':il;i; >zoic I,:iine!Iihranchs.— Aft«;r Hillitiys. 



J Ciicullea npitiia. 2, Niinila ohlnn^a. 3, Nnoila liuratn. 4, Cypriinrdia trunaxta 

 5, Tellina ovata. 6, Niuula bellatula. 7, Modiola coiuciilrua. 



and is ever ready to correct its errors when fresh light or new 

 discoveries make such necessary." 



The ordinary bivalves, like the mussels and cockles, now so 

 very plentiful on our coasts, are rare in the Cambrian and Silu- 

 rian, and for the first time make a somewhat consjjicuous 

 appearance in the Upper Silurian and Devonian. liut from 

 the first they resemble very closely their modern successors, 

 though on the whole neither so large nor so ornate (Fig. 6i) 



