736 Mr. Lonsdale on the Age of the 



and I beg to add, that the list just mentioned was evidertly prepared with the 

 utmost care and scrupulous attention to the characters of the fossils, and 

 without the least appearance of bias to preconceived opinions. The amount 

 of species is twenty -.—Fenestella antiqua (Retepora prisca, De Verneuil) ; 

 Aulopora tubaformis {A. conglomerata, De Vern.) ; Favosites poli/morpha, 

 F. spongites (Calamopora spongites, De Vern.) ; Cj/athophj/llum turhinatum 

 (includino- C. radicans), C. ccpspitosum ; Strombodes vermicularis {Cyatho- 

 phyllum vermiculare, De Vern.); Ast?^ea ananas {C. ananas, De Vern.); 

 Serpula omphaloides, Orthis transversalis ? 0. umbraculum {Spirifera cri- 

 nistria, Phillips) ; Spirifera atienuata, Terebratula prisca, T. aspera, T. 

 concentrica, T. plicatella, Producia acu/eata, Terebra Hennahii, Euomphalus 

 radiatus, and Orthis similis*. 



The distribution of the twenty species contained in the above list, is as 

 follows : — 



One, — Orthis umbraculum, is also a mountain-limestone shell. 



Five, — Strombodes vermicularis, Terebratula concentrica, Spirifera attenuata (not the mountain- 

 limestone shell), Terebra Hennahii, and Euomphalus radiatus, are true Devonian fossils. 



Seven, — Fenestella antiqua, Favosites polymorpha, F. spongites, Cyatliophyllum turbinatum, C . ccx- 

 spitosum, I'erebratula prisca, and T. aspera, occur both in the Devonian and Silurian systems. 



Two, — Aulopora tubceformis and Astrea ananas, have not yet been seen by me in the Devon- 

 shire collections. 



The Orthis transversalis is distinct from the Leptcena transversalis of the 

 Silurian system, and the Terebratula plicatella is believed to be distinct from 

 the Terebratula borealis of the same system. 



The Producta aculeata {P. subacuta, De Verneuil), Serpula omphaloides, 

 and Orthis simi/is, have not yet been noticed by me in England. 



The inference which 1 think may be drawn from the above enumeration 

 is, that there exists in the Boulonnais a series of beds characterized by a 

 suite of fossils intermediate between that of the Silurian system and that of 

 the mountain-limestone, or on a parallel with the old red sandstone. 



The preceding remarks partake too much, I fear, of the tone of personal 

 advocacy ; but it was my duty to show what share I have had in the deve- 

 lopment of the Devonian or old red system. How small my share is, I need 

 not say — how large that of Professor Sedgwick and Mr. Murchison, will soon 

 be known to all. 



* The three last species are added from a collection of Boulonnais fossils in the cabinet of 

 M. Bouchart, and which I have been permitted to examine since the reading of the paper (May, 

 1840). A fuller list of the Boulonnais shells will appear in Mr. Murchison's paper, " Sur les 

 Roches Devoniennes qui se trouvent dans le Boulonnais et les pays limitrophes," and which will 

 be published in the forthcoming number of the Bulletin of the Geological Society of France. 



