and species of Silurian Radiata. 275 



Strephodes Craigensis (M'Coy). 



Sp. Char. Corallum forming irregular, slightly flexuous, slowly 

 tapering, obscurely nodulose subcylindrical stems, averaging 

 7 or 8 lines in diameter when old, but both at that size and at 

 3 to 4 lines in diameter, tapering at the rate of 1 Hne in 1 inch ; 

 outer wall thick, marked with longitudinal fine lamellar sulci 

 (ten in 3 lines) ; terminal cup shallow, lined by the radiating 

 lamellae, which are strongest a little within the circumference, 

 and are obscurely complicated at the centre ; connected at the 

 sides by distinct transverse vesicular plates : horizontal section, 

 outer solid wall thick, sixty -five to sixty-eight slightly flexuous, 

 radiating lamellse, one haK of which extend about half-way to 

 the centre, the other half slightly thickening, uniting in groups 

 of two or three and compUcated at the centre ; transverse vesi- 

 cular plates few, most numerous towards the circumference : 

 vertical section shows a thick external wall on each side, from 

 which rows of depressed elongated irregular cells curve gra- 

 dually under the centre, the plates being thickest and neai'ly 

 horizontal in the middle half of the diameter. 



In the greater thickness, size, and approximately horizontal 

 disposition of the vesicular plates in the middle of the corallum, 

 there is an approach to Cyathophyllum, but in the cup and hori- 

 zontal section the radiating lamellse are clearly seen to unite in 

 bundles and reach the centre — characters totally at variance with 

 those of Cyathophyllum. On some of the slender stems obscure 

 signs apparently of lateral buds appear, but I cannot be certain 

 of their true nature. It tapers more slowly than any other spe- 

 cies I know. 



Common in the limestone of Craig Head. 



Sti'ephodes vermiculoides (M'Coy). 



Sp. Char. Corallum of closely grouped, round columns of ex- 

 ceedingly irregular diameter from frequent intermittence of 

 growth, producing very unequal annular swellings and fun- 

 nel-shaped rings ; external wall thin, marked by lamellar sulci 

 (six in 3 lines at a diameter of 1 inch, or about twenty all 

 round, indistinct at the more usual diameter of 8 or 9 lines) ; 

 cup deep, hned with alternating large and smaller vertical 

 lamellse irregularly uniting about the centre, their edges and 

 sides papillose and perforated, the union of which papillae forms 

 a dense broad granular margin to the cup obscuring the la- 

 mellae : horizontal section, about twenty slightly and irregu- 

 larly curved, flexuous, radiating lamellae, extremely thin, indi- 

 stinct and equal in the dense, nearly solid or granular outer 

 area, where they are connected by very close, minute, curved. 



