SILURIAN RADIATA. 159 



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 line in 1 inch ; 

 outer wall thick, marked with longitudinal fine lamellar sulci 

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

 lamcllse, 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 half of which extend about half-way to 

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

 of two or three and complicated 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 nearly 

 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. 



{Col. University of Cambridge.) 



Strephodes pseudo-ceratites (M^Coy). 



/SJ?. Char. Corallum small, simple, curved, conical, obscurely 

 wrinkled concentrically; ordinary specimens about 1 inch 

 3 lines long, and 9 lines in diameter at that distance from the 

 apex, rarely exceeding that diameter, though occasionally 

 longer ; outer wall with faint vertical lamellar sulci, nine in 

 3 lines, at 9 lines in diameter, or about sixty -five all round : 

 horizontal section shows a dense, nearly solid, outer area less 

 than one-third the diameter of the tube, in which the radia- 

 ting lamellse and the excessively close fine vesicular connecting 

 plates are obscure ; an inner circular area about half the dia- 

 meter, into which only thirty-two to thirty-four (or each alter- 

 nate one) of the radiating lamellse penetrate, uniting irregu- 

 larly and slightly twisted about the centre, connected by very 



