and species of Silurian Radiata. 281 



obscure traces of cells seem doubtfully visible under the lens ; — 

 if these should prove to be vesicular plates, the species should be 

 transferred to the genus Strephodes, thus removing it still further 

 from P. bina, in which there is nothing of the kind. 



Var. a. gracilis. 

 Certain casts a little longer and of a much more elongate form 

 than the above, being about as high as wide, and having about 

 thirty to thii-ty-six primary lamellar slits at a diameter of 6 or 

 7 hues, and an equal number of rows of close, small puncta, re- 

 quire separate mention, though I do not see that they differ in 

 other respects. 



Common in the schists of Pen lar Llandovery ; Mathyrafal ; 

 Llansaintfraid and Castel Craig ; fine Caradoc sandstone of Alt y 

 Anker. 



Cyathaxonia Siluriensis (M^Coy). 

 Sp. Char. Corallum elongate conic, about 5 lines long and 2 

 lines in diameter at that height from the base; strong central 

 axis nearly one-third of the diameter; sixteen or seventeen 

 strong radiating lamellae, each extending from the axis to the 

 outer wall, before reaching which it bifurcates, leaving a tri- 

 angular interlamellar space about equal in width to the di- 

 stance between the adjoining lamellae ; surface coarsely ridged 

 longitudinally ; the sulci corresponding to the divided edges 

 of the lamellae, leaving one of the equal intervening ridges to 

 correspond with each of the spaces between the individual 

 lamellae, and between their divided edges. 



This is the only species of the genus I am aware of in the 

 Silurian rocks. 



Rare in the Upper Ludlow rock of Underbarrow, Kendal. 



Spongarium (equistriatum (M'Coy). 



Sp. Char. Elliptical, depressed, proportion of width to length 

 varying from 85 or 90 to 100 ; marked with sharp, rugged 

 concentric wrinkles ; entire disk closely and evenly radiated by 

 coarse rounded very approximate ridges, averaging five in 1 line. 

 Long diameter from 8 lines to 1 inch. 



This species is perfectly distinguished from its congeners by 

 the coarse, close, equal striation of the entire disk, giving it a 

 peculiarly harsh aspect ; the ridges are much less than their thick- 

 ness apart. 



Rather rare in the quartzose Upper Ludlow rock of Benson 

 Knot, Kendal. 



Spongarium interlineatum (M'Coy). 



Sp. Char. Broad oval, usual proportion of width to length as 

 Ann. Ss Mag. N. Hist. Ser. 2. Vol.yi. 19 



