EXPLANATION OF PLATE 1. F. 



LOWER PALiEOZOIC CRUSTACEA. 



1 BARRANDIA CORDAI (M<^Coy). From the black shale of Builth. 



1 a Two thoracic segments of do. magnified, to shew the coincidence of their form and pleural 



furrow with Ociygia. 



2 OGYGIA RADIANS (M'^Coy). Pygidium, natural size from the black shales of Pen Cerrig, Builth. 



2 a The same magnified, to shew the fine duplicating furrows, as in Oqygia generally. 



3 ISOTELUS AFFINIS (M<^Coy). Pygidium and thorax natural size, from the fine slates over the 



Iron works of Tremadoc. 



4 CALYMENE BRE VIC A PIT ATA (Port.) Cephalic shield from the schists of Nant yr Arian 



(antennae punctures distinct at each side near the front of the glabella). 



5 Pygidium of do. from the same mass. 



6 Profile of head of the same from schists of Applethwaite Common. 



7 CALYMENE PARVIFRONS (Salt.) Cephalic shield from the trappean schists of Tahu-ion. 



7 a Profile of do. 



8 CALYMENE BAYLEI (Bar.)? Cephalic shield from the fine sandy schists of Tre Gil (antenna 



punctures distinct at each side near the front of the glabella). 

 8 a Profile of do. 



8 b Granulation magnified, from the flat plate in front of the head of a specimen from the limestone 



of Golden Grove. 



9 CALYMENE SUB-DIADEMATA (M-^Coy). Imperfect head, natural size, from the limestone of 



Leintwardine. 



9 a Profile of do. 



10 Variety, small perfect specimen from the calcareous schists of Coniston Water-Head. 



10 a Profile of do. magnified, shewing the great width of the side portions both of the head and body. 



11 CERAURUS CLAVIFRONS (Dal. Sp.) Small specimen of glabeUa, shewing the extent of the 



segmental furrows, from the limestone of Llvvyn y Ci. 

 11 a Profile of do. 



11 5 Granulafionof do magnified. 



12 Glabella and part of cheeks of large crushed specimen, from Applethwaite Common. 



13 CERAURUS WILLIAMSI (M-'Coy). Entire animal from the schists of Goleugoed Myddfai. 

 13 a Profile of do. 



13 h Two pleurae and portion of axis magnified. 



14 ECCOPTOCHILE SEDGWICKI (M^Coy). Natural size, from the black shale 3 miles N. of Builth. 



1.5 STAUROCEPHALUS MURCHISONI (Bar.) Glabella and part of cheeks natural size, from Rhiwlas. 



15 « Magnified. 



16 TROCHURUS NODULOSUS (Salt. Sp.) Pygidium, natm-al size from the schists of Pont y Glyn, 



Diffwys. 



17 LICHAS SUB-PROPINQUA*. Pygidium, from the limestone of Coniston. 

 17 « Granulation of do. magnified, to shew the pointed rather distant granules. 



* Since the description was printed, M. Barrande informs me that the apex of his L. propinqica is notched a 



character which I mentioned he had omitted in his description, but which prores the present species distinct. 



