BRITISH SILURIAN BRACHIOPODA. 87 



all, that I was able to bring it safely home. At last I had it securely embedded on the 

 venti-al side in plaster-of-Paris, and it was in this condition that Sir Roderick 

 Murchison saw it. I little thought then of the numberless experiments and of the great 

 trouble this species would cost me before it received its present designation of Whitfieldia 



" These details may seem to be of little value to the reader, but they refer to my 

 first connection with the spiral processes of the Brachiopoda, and from that time my 

 interest in the matter has never ceased, and for many years I have made every experiment 

 I could devise to find out a way of developing these interesting and important internal 

 appendages. One thing I discovered most certainly by the fracture of numerous 

 specimens, and that was, that the occurrence of the spiral processes in the Carboniferous 

 and Silurian Brachiopoda was by no means uncommon ; but the difficulty still remained 

 of clearly developing them so as to reveal not only their shape but also their connections. 



" In 1877, a deep cutting was formed for a railway branch near Walsall, and I had 

 many opportunities there of collecting Silurian Brachiopoda, especially large numbers of 

 Meristella tuniida, which occurred in an abundance I have rarely seen equalled as 

 to any species of fossil shells. By the careful chipping of the dorsal valve of specimens 

 of Sjjirifera plicatella, Atrypa reticularis, and Meristella tmnida, found in this locality, I 

 was able in some cases to reveal the spirals in the same condition as in the specimen of 

 Meristella tumida I found at Pen-y-llan, but I could not get at the connections, and the 

 spirals were very much obscured by the coating of crystallised carbonate of lime sur- 

 rounding them. I had observed that in many of the specimens the spirals were entirely 

 surrounded by a solid matrix of spar, and at last I found out the way, by the use of a knife 

 and water and hydrochloric acid, to develop distinctly in such cases not only the spirals 

 but their connections with the hinge-plate of the dorsal valve, and their connection with 

 each other. My first specimen I sent to Mr. Davidson in 1878, and since then I have 

 gradually perfected the process, some of the results of which the readers will see in this 

 Supplement. 



" Perhaps it may be as well at first to give a short description of the different con- 

 ditions as to matrix in which the spirals may be found. Sometimes the shell and 

 spirals are sihcified, whilst the matrix involving the spirals is calcareous. It is said that 

 this was the condition of the specimens of Spirifera striata in the Cambridge Museum, 

 which, as shown in Mr. Davidson's figures, so perfectly and beautifully reveal the spirals. 

 These specimens were developed, it is stated, by acid, and were found somewhere in 

 England ; but after every possible research, and after having had thousands of specimens 

 pass through my hands of the Silurian, Devonian, and Carboniferous Brachiopoda, I have 

 not been able to find a single British specimen in the same condition. Mr. John Young, 

 of the Hunterian Museum, Glasgow, has sent me some siliceous casts of Atliyris Boysii 

 from which the shell and spirals had been decomposed ; and Mr. Davidson, in his 

 ' Carboniferous Monograph,' refers to siliceous casts of Spiri/erina minima and Athyris 



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