THE GEOLOGICAL RECORD. 139 



continuous through the whole interval ; every single 

 deposit in the entire series since the Silurian must have 

 been contemporary with some of the sponges; and, as 

 a matter of fact, Mr. Parfitt's statement, however true 

 of the condition of our knowledge a few years back, 

 must now be qualified by the addition of several species 

 spread over the interval in Britain alone, even if we 

 exclude some indefinite structures, of which no opinion 

 can be at present pronounced with safety. Mr.* Parfitt 

 himself, in a paper read at Honiton in 1868, remarks 

 that ' the Devonian formation has furnished a great 

 number of specimens of what appear to be species of 

 sponges.' From Permian and Triassic beds on the con- 

 tinent of Europe, a very large number of forms are 

 said to be more or less distinctly made out. Mr. Salter, 

 in 1864, reported the discovery of Protospongia Fene- 

 strata-in the Lingula flags of St. David's, thus carrying 

 back this form of life beyond the Silurian to the Cam- 

 brian era. It is an interesting illustration of the great 

 ambiguity of these ancient fossils, that two such autho- 

 rities as Mr. Salter and Dr. Bowerbank differed about 

 the Protospongia, the one supposing it to exhibit the 

 spicules, the other the fibre of the sponge. The simple 

 facts that species have to be moved backwards and 

 forwards between the amorphozoic and zoophytic groups, 

 that relics may pass for fish in one year and sponges 

 in another, and by-and-by be recognised again as fish, 

 show the often imperfect condition of the record, even 

 where it is not a complete blank. 



Where direct evidence of any kind is still unavailable, 



