BY MRS MILLER. xll. 



low boue-bed, with the Aymestry Limestone intervening, lie 

 the Lower Ludlow rocks ; and there, in 1859, the Rev. Mr 

 Lee of Caerleou, in company with Mr Lightbody of Ludlow, 

 found a Pteraspis, — a genus closely allied to the Cephalaspis, 

 ^in the quarries of Leintwardine, Herefordshire. Regard- 

 ing this, the Rev. Mr Symonds of Pendock writes me, — 

 " I visited the quarry, at the request of Sir C. Lyell, and 

 svas shown the spot from which the specimen was procured, 

 by Mr Lightbody. There can be no doubt about the strata 

 belonging to the Lower Ludlow rocks of Murchison, and 

 some characteristic fossils are imbedded in the same slab 

 which contains the Pteraspis."* 



Not only from this, but owing to some other circumstances, 

 which we shall presently endeavour to explain, the family 

 of the Cephalaspidse have risen into much more importance 

 than they possessed at the date of the " Foot-prints." Ce- 

 phalaspis ornatus, and Auchenaspis, another closely-allied 

 genus, were found in another Ludlow bed, occupying a rather 

 higher level than the original one, before the publication of 

 Sir Roderick Murchison's last edition of " Siluria." (See 

 " Siluria," p. 155.) In the tilestones or transition beds be- 

 tween the Siluria and the Old Red, Cephalaspis and Pteraspis 

 again appear. " In Shropshire," says Sir R. Murohison, in 

 recounting many instances of the same nature, — " in Shrop- 



* ** No one," says Mr Symonds, in a quite recent work, entitled *• Old 

 Bones, or Notes for Young Naturalists," " save the geologist, who knows 

 the thickness of the Upper Ludlow shales, and the Aymestry limestone 

 which intervenes between the site of the deposition of the Pteraspi* 

 truncatus and that of the Pteraspis Ludensis, can adequately comprehend 

 how much the discovery of this little fish antedates the period during 

 which fish have now been proved to have existed on our planet." 



