BRITISH FOSSILS. 



5 



wick's intended memoir on the fossils of Westmoreland and Wales ; 

 and a short description of it will be found in the Appendix to the 

 second fasciculus of his large work on the " British Palaeozoic rocks \' 

 it is also described by Professor M'Coy, in the first fasciculus, as 

 Zethus sexcostatus. 



British Localities and Geological Range. — Llandeilo Flags- 

 Rhiwlas and Llwyn-y-ci, north-west of Bala Lake ; and Llechwedd 

 Ddu, east of the lake, North Wales ; in the former locality very 

 abundant ; Sholes Hook and Pelcombe Cross, Haverfordwest. Not 

 yet found in Ireland. 



Explanation op Plate IV. 



Fig, 1. Coiled specimen ; from Ehiwlas. 



Fig. 2. Do. ; back view, to show the 1 1 thorax segments. 



Fig. 3. Do. ; showing the raised fascia a. 



Fig. 4. Do. ; side view. 



Fig. 5. Imperfect head ; the dotted lines are added from other specimens ; the cheeks 



show the pitted surface. 

 Fig. 6. Magnified portion of head. 



Fig. 7. A thorax segment enlarged ; at a, the fulcral point ; h, the facetted surface, and 

 c, the blunt indented tip, as usual in the genus ; they are added in dotted lines 

 as the specimens are not perfect enough to show them. 



Fig. 8. Side view of the pleurae in the coiled state ; at a, one of the facetted surfaces is 

 seen by the breaking away of the other segments. 



Fig. 9. Tail of a Khiwlas specimen. 



Fig. 10. Part of the same, magnified, to show the scabrous surface. 

 Fig. 11. Variety of tail with 7 side ribs. Rhiwlas. 



Fig. 12» Internal cast of variety with the central part of the axis more free from ribs. 

 Sholes Hook. 



Fig. 13. Front view of the head, slightly enlarged, of E. variolaris, to show the course 

 of the facial suture in front of the head, and the vertical suture b, which 

 divides the cheeks, filled at its lower end by a narrow triangular rostral 

 shield. Wenlock limestone of Dormington, Woolhope. 



Fig. 14. The same, a side view ; a a, facial suture. 



Fig. 15. Under view, somewhat enlarged, of the tail of E. punctatus* to show the 

 incurved scabrous margin which unites the lateral ribs of the tail ; their free 

 points are seen projecting beyond it. Walsall, near Dudley. 



Fig. 16. Hypostome of do., enlarged ; a, sinuated margin ; b, cucullate base ; c, the 

 points of the extended base of attachment. Walsall. 



The above figures are all from specimens in the collections of the Geol. Survey. The 

 last four figures are enlarged to once and a half their natural size. 



JVotes on the other British species of the Genus. 



If the strict rule of priority were observed, irrespective of clear definition, we should be 

 compelled to adopt the name Cryptonymus for this genus, as that of Zethus for Cybele. 

 Dr. Kutorga, indeed, in the journal above quoted (1848), advocates this course, and has 



* See description at the end. 



