140 



>IHE GEOLOGIST. 



position, &c, of the fish figured are as nearly as may be those of" the 

 specimen from which it is copied, other specimens show a considerably 

 stouter body. The scales are of course restored, only small patches 

 of these being preserved on any of the specimens. The dotted lines 

 meant to show the probable size of the caudal and dorsal fins, unless, 

 indeed, that figured as a dorsal had really formed only part of the 

 large tail-fin. — I am, your obedient servant, Jas. Powrie, F.G.S., 

 Reswallie, Forfar. 



REMARKS ON MR, ROBERTS' PAPER ON CEPHALASPIS. 



g IRj — I venture to send you a few comments on Mr. George 

 Roberts's paper on Cephalaspis in your last number. 



How your correspondent, Mr. G. E. Roberts, can talk (page 103) 

 of the Lower Ludlow at Leintwardine being " clearly marked out as 

 a littoral deposit" by its " starfishes," after his paper in the " Geolo- 

 gist" the other day announcing the discovery of starfish at one 

 thousand two hundred and sixty fathoms depth, surprises me much. 



Equally does it surprise me (especially since his connexion with 

 the Geological Society) to find him talking of the " Tilestone series 

 passing into the underlying Silurian," when Sir R. Murchison, in 

 his last edition of Siluria, has laid down (though, T confess, with a 

 little confusion) that the beds between the Old Red and the Silurian 

 are to be called Passage beds, and are quite different from his original 

 Tilestones, which are clearly Upper Ludlow, being Downton Sand- 

 stone. As long as this inattention to proper nomenclature is per- 

 petuated, no one can understand what is written on the subject. 



The chief cause of error seems to lie in the end of the tenth 

 chapter of Siluria, which appears to have been written before the 

 present knowledge on the subject was obtained, and not corrected 

 before sending it to press. The author there certainly speaks of the 

 Tilestones and Passage beds of King-ton in connexion with Mr. 

 Banks ; but those beds at Bradnor Hill are unquestionably Downton 

 Sandstone. They were formerly by some called "Transition beds" 

 (as marking the change to sandy from shaley beds), and were then 

 considered to be equivalent to the Tilestones of Murchison, and which 

 Tilestones were afterwards considered by some to be the same as the 

 Passage beds, which, in fact, lie some distance above them. There 

 is no excuse fin- the mistake on the part of my friend Roberts, who 

 knows both series of beds well, and I am sure can see no similarity 

 between bhem. In fad (at page 106), he calls the Kington beds 

 Downton, but oddly enough distinguishes between the Downton beds 

 ami the Upper Ludlow, of which they are the top. In the same 

 page (at top) he speaks of Cephalaspids being " abundant in the 

 neutral ground between the Downton and the Tilestones,' 7 which 



