4 



BRITISH FOSSILa 



authors, and from his figure and description, T. granulafus differs 

 in the thicker crust, and in the size, different shape, and greater 

 extension forwards of the glabella, which invades the area of the 

 fringe in front, while in our species it scarcely ever reaches to it. 

 The width of the axis, too, in the tail and thorax, is considerably 

 greater, and the tail, though like in shape, is destitute of lateral 

 fiirrows, and at its margin is steeply bent down (" prsecipiti''). The 

 punctation of the head (if indeed Lov^n's specimens were perfect in 

 this part) shows but three or four rows at the most, and the outer 

 row much enlarged (probably having two puncta in a common 

 depression) while in ours they are numerous and of nearly equal 

 size. 



History. — First described by Sir Roderick Murchison from spe~ 

 cimens gathered at Llangadock by the Rev. Henry Lloyd, after 

 whom the species is named ; this figure, however, though charac- 

 teristic, was from a specimen with but five rings, evidently an 

 accidental growth. The peculiarity, however, was noticed by 

 Lovdn,* who doubted its identity with his T. granulatus from this 

 circumstance. Burmeister had previously, in 1843, united it \Mth 

 the Swedish species, and in accordance with his suggestion and from 

 the great general similarity of the pendant ears and rounded tail, it 

 was named T. granulatus by myself in the " Journal of the Geo- 

 logical Society,'' and in the lists drawn up by Professor Phillips and 

 myself in the Survey Memoirs. I am glad now, from good spe- 

 cimens, and more close observation, to correct the error. 



British Localities and Geological Position. — Liandeilo Flags. 

 In Carmarthenshire ; Dynevor Park, and Mserdy bach, Llandeilo * 

 Blaen-dyffryn-garn and Coed Sion quarries, Llangadock, abundant ; 

 in Shropshire, Middleton and the country about Chirbury and 

 Shelve, also plentiful. 



ExPLAJfATION OF PLATE VIL 



rig. 1. Perfect specimen, from the Coed Sion quarries, Llangadock. Presented to the 

 Museum of Practical Geology by the Eev. H. Lloyd. 



Pig. 1*. The same, magnified, sho^ving the concave fringe perfect on the right hand of 

 the specimen, and on the left, at a, the hollow impression left by its convex 

 lower surface. The thorax and tail are represented as separate from the 

 head ; and at b, the abruptly vertical margin of the tail is just visible at the 

 recurved tip. 



Pig. 2. A small specimen of the var. j8, with the fringe flattened above (from pressure ?) ; 

 the ears in this variety are much smaller than in the ordinary form. 



* Ofversigt Kongl. Vetenskaps Akad. (1845), 109, pL 2. f. 2. 



