BRITISH FOSSILS. 



5 



fossils. His specimens were not perfect enough to enable him to 

 see the true position of the large eyes on the head, nor the strong 

 granulation of the glabella, and he referred it therefore, with a 

 doubt, to the genus Harpes, suggesting that it might form a new 

 group allied to that genus ; this idea was carried out in his classifi- 

 cation of the British Trilobites, in the Annals of Natural History, 

 for December 1849, in which this trilobite stands as the type of a 

 proposed new genus, Harpidella, and the granulated surface is 

 mentioned. In a communication from him lately, he is agreed with 

 me in identifying these perfect specimens with those described by 

 himself It is mentioned by myself, Proceed. Brit. Assoc., 1852, 

 Sect. p. 57. 



British Localities and Geological Range. — Llandeilo Flags to 

 Lower Ludlow Rock. In Llandeilo flags ; sandstones of Ardaun, 

 Boocaun, Cappacorcogue, and Tonlegee, Cong, county of Galway 

 (Mr. Griffiths' collection) ; limestone of Portrane, county of Dublin ; 

 sandstones of Mullock quarry, near Girvan, Ayrshire (M'Coy) ; Bala 

 limestone of Cader Dinmael, near Corwen, North "Wales ; in the 

 Wenlock limestone and shales of Dudley and its neighbourhood 

 (figs. 2-6); in the Wenlock shale, west of the Worcester Beacon, 

 Malvern Hills ; Lower Ludlow rock, of Hole Farm, near Philsley 

 Beauchamp, Abberley HiUs (fig. 1). [Survey Collection]. 



Explanation of the Plate. 



Fig. 1. A nearly perfect specimen, from the Lower Ludlow Rock, Abberley ; natural 

 size. 



Fig. 1*. The same, enlarged. The tail in this figure is rather too large, both as to 

 length and breadth. 



Fig. 2. A fine specimen from Dudley, in the collection of T. W. Fletcher, Esq. 



Fig. 2*. The head, magnified, and dissected at the suture. The glabella and its basal 



lobes are in this of the usual form. 

 Fig. 3. A variety from Dudley (Mr. Gray's coll.), in which the glabella is shorter and 



more parabolic in outline ; it is a rare variation. 

 Fig. 3*. The same, magnified. 



Fig. 4. A fragment from Dudley, placed laterally in the rock, and showing the dorsal 

 spine parallel to the body, and reaching to the tail. (Mr. Gray's cabinet.) 



Fig. 5. Magnified dissections of the thorax ; a, the anterior segment, with its pleursB 

 obliquely truncate at their ends ; b, the 6th segment, showing the broad deep 

 pleural groove and the long dorsal spine ; c,the last or 11th segment ; e, the 

 small transverse tail. 



Fig. 6. A lateral view of the head, magnified. 



Fig. 7. A specimen, from Dudley, with the dorsal spine greatly elongated. Natural size, 



and enlarged. (Mr, Fletcher's coll.) 

 Fig. 8. A head from Cader Dinmael, Denbighshire ; Bala limestone. Natural size, and 



enlarged. 



