104 BRITISH PALEOZOIC SPONGES. 



the limestones only the microscopic detached skeletal-spicules of Sponges have been 

 preserved. 



Permian System. — It is doubtful whether any genuine fossil Sponges have as 

 yet been discovered in the strata of this system in the British area ; those described 

 as such by the late Prof. King 1 prove, on examination, to be either organisms of 

 very problematical character or inorganic concretions. The forms described as 

 Sponges by Prof. Geinitz 2 from the corresponding Dyas of Germany, are of an 

 equally dubious character. 



1 ' Monog. of the Permian Fossils,' Pal. Soc, 1849, pp. 11 — 14. 



2 ' Die animalischen Ueberreste der Dyas,' 1861, pp. 123-4, pi. xx. 



