120 Mr. F. M^Coy on some new genera and species of 



produced by a bipartite division of the parent stem parallel to 

 one of its faces : polyps distinctly separated above. 

 The corals of this genus bear precisely the same relation to 

 Nemaphyllum that StylastrcRa (Lonsd.) does to the Lithostrotion 

 of the same writer (Strombodes) with regard to their mode of 

 development, that is to say, in Nemaphyllum, as in Strombodes, 

 the increase is by circular buds developed within the walls of the 

 parent stem, the polygonal walls being gradually perfected by the 

 joint labour of adjacent polyps ; which it is inferred from their 

 mode of growth, had a community of existence and organic 

 union at the surface, and from the same cause the columns have 

 no outer surface to exhibit in a rough fracture, but break 

 through the middle rather than separate one from another. In 

 the Stylaxis however, as in the Stylastrcea, the new columns are 

 produced by a sudden splitting of one of the columns into two, 

 the divisional lines commencing along the middle of one face and 

 going directly across to the opposite face, distinctly separating 

 the young four- sided column at once by a double-plated, recti- 

 linear boundary- wall parallel with one of the faces ; the external 

 striae of the old column being traceable upwards into the young 

 one. The columns are easily separable one from another in the 

 rough fracture, and the polyps are inferred to have been distinct 

 from each other, and each to have constructed independently its 

 own boundary-wall. 



Stylaxis major (M^Coy). 



Sp. Char. Tubes averaging 6 lines in diameter, mostly hexago- 

 nal, external surface coarsely striated longitudinally and trans- 

 versely marked with strong curved irregularities of growth, 

 the convexity of the curves upwards : horizontal section, sixty- 

 three slender radiating lamellae converging from the walls to- 

 wards the flat central style or axis, which is about 1 line in 

 width ; one half of the lamellae reach the centre, the inter- 

 vening ones reach halfway; outer area exhibiting numerous 

 transverse vesicular plates between the radiating lamellae : ver- 

 tical section, axis straight, ribbon-like ; inner area broad, of 

 slightly curved vesicular plates forming rows of lengthened 

 irregular cells, extending obliquely downwards and outwards 

 from the axis, about three in a row ; outer area of rows of 

 small hemispherically-curved plates, including small rounded 

 cells extending very obhquely upwards and outwards, about 

 six in each row. 

 This species is remarkable for the large size of its tubes and 



great number of the radiating lamellae. 



From the carboniferous limestone of Derbyshire. 

 {CoL University of Cambridge.) 



