160 SILURIAN RADTATA. 



few, thin, vesicular plates : vertical section^ the nearly solid 

 outer area as above (about half an inch of the apex often also 

 filled with solid matter), inner area traversed by numerous de- 

 pressed small irregular cells, arranged almost horizontally, or 

 with a slight upward curvature. 



This species almost exactly resembles the small variety of the 

 Devonian Cyathophyllum ceratites of Goldfuss (which I also find 

 to be a Strep hodes, thus differing from his larger variety to which 

 I restrict his name), but is readily separated by its closer and 

 more numerous lamellae (that having only thirty-seven lamellse 

 at the above diameter). The Streptoplasma corniculum (Hall), 

 from the Trenton limestone, is still more closely allied, but as it 

 is impossible to be certain of the species of those turbinated corals 

 without knowing their internal structure, I cannot venture to 

 unite our British species, which I have worked out, with the 

 American one, in which that has yet to be done, and of which I 

 have no specimens to do it. 



Common in the limestone of Old Radnor, Presteign, Radnor- 

 shire ; Wenlock limestone of Dudley, Staffordshire and Sedgley. 



{Col. University of Cambridge.) 



Strephodes trochiformis (M^Coy). 



Sp. Char. Corallum simple, slightly curved, widely turbinate, 

 average length 1 inch 3 lines, and width at mouth 1 inch 

 1 line, with irregular swellings of growth ; outer wall very thin, 

 marked with equal lamellar sulci (six in 3 lines at 1^ inch in 

 diameter, or eighty-three all round) ; terminal cup very deep, 

 conical, margin rounded, sides gradually sloping, lined by the 

 thin, alternately longer and shorter uneven-edged lamellse, the 

 longest of which are irregularly blended at the centre, con- 

 nected throughout by numerous curved transverse vesicular 

 plates : horizontal section shows the same characters as the 

 terminal cup, the alternate lamellse extending about half way 

 to the centre : vertical section, apex filled with solid matter, 

 centre with irregular vermicular lines (the sections of the com- 

 plicated edges of the radiating lamellse), from thence to the 

 walls made up of small, thick, rounded, vesicular plates, the 

 obscure rows having a slight downward curve. 



One worn specimen from Dudley, in the collection of Count 

 Miinster, was considered by him and Dr. Goldfuss to be a variety 

 of the Cyathophyllum dianthus (Goldf.) of the Devonian rocks, 

 from which I find it differs generically. 



Not uncommon in the Wenlock limestone of Dudley, Stafford- 

 shire. 



[Col. University of Cambridge.) 



