72 



PALEOZOIC CORALS AND FORAMINIFERA. 



diameter of the adult little more than an inch^ and which it 

 attains at two inches long, remaining nearly cylindrical after 

 that length; surface closely striated longitudinally, about fifteen 

 strise in one-fourth of an inch, corresponding in number with 

 the radiating lamellae : horizontal section, inner area rather 

 more than one-third the diameter, of small, closely blended, 

 vesicular plates ; outer area with 180 radiating lamellae, ninety 

 of which reach from the wall to the edge of the inner area, and 

 ninety intermediate ones only reach half way ; intermediate 

 transverse vesicular plates very delicate : vertical section, inner 

 area defined by rather thick walls ; it consists of minute, com- 

 pressed, elongate cells, arranged in transverse curved rows, 

 the convexity of the curve upwards ; outer area, large cellular 

 structure, inclining upwards and outwards. 



Rather common in the carboniferous limestone of Derbyshire. 

 {Col. University of Cambridge.) 



Strephodes (M^Coy), n. g. 



Etym. arpe^co, torqueo (from the twisting of the lamellae 

 about the centre). 



(Strombodes pars of Lonsdale, not of Schweigger.) 



Gen. Char. Corallum simple and conic, or compound and form- 

 ing rounded masses of 

 inseparably united poly- 

 gonal cells; in either case 

 the terminal cup is deep 

 with numerous equal, ra- 

 diating lamellae, conver- 

 ging fi-omthe walls to the 

 centre, where they meet 

 and are complicated, 

 usually twisted in bun- 

 dles about an imaginary 

 axis ; vertical section, 

 small vesicular struc- 

 ture, the rows of cells ar- 

 ranged in a semielliptical 

 curve, convexity down- 

 wards, descending from 

 the sides at a steep angle 

 and rounding under the 

 centre, where the-^ cells Strephodes: a. vertical section and ternii- 

 are a little larger than nal cells of compound species ; b. do, sini- 

 at the sides : horizontal P-^ species. 





P 



