14 OUR COMMON BRITISH FOSSILS. 



now. This accounts for the difficulty some of our 

 best naturalists find in assigning certain fossils to 

 their true classification. Thus, Mr. Carter thinks that 

 Parkeria (a not uncommon fossil in the Upper Green- 

 sand of Cambridgeshire, and which was originally 

 described by Dr. Carpenter as a gigantic foraminifer 

 an inch in diameter, whose walls are composed of 

 cemented grains of sand instead of " shell ") is in 

 reality a hydrozoon allied to the pretty Hydractina 

 found coating the outsides of many living whelk shells. 

 The same naturalist believes that Stromatopora is of 

 similar character. The latter is a very abundant fossil 

 in the Devonian limestone. In the quarries at 

 Newton Abbot one can hardly pick up a piece of 

 stone which does not contain some species of Stroma- 

 topora. It is ^found in the Silurian, Devonian, and 

 even' Carboniferous limestones. The beautiful flesh- 

 tinted marbles obtained from the Devonian limestones 

 near Torquay, when polished, show excellent sections 

 of Stromatopora. How this fossil has been bandied 

 about from scientific pillar to scientific post ! For a 

 long time it was regarded as a species of coral. Then 

 it was supposed to be a calcareous sponge. Next it 

 was imagined it might be somehow intermediate 

 between the hexactinellid sponges and such hydrozoan 

 corals as the recent and abundant Millepora. Professor 

 Nicholson threw out the hint that this fossil might be 

 related both to sponges and foraminiferse ; whilst Pro- 

 fessor Sollas holds to its being a hexactinellid sponge* 



