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 Stylastrea (Lonsd.) does to the Lithostrotion 
of the same writer (Strombodes) with regard to their mode of 
development, that is to say, im 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 haye 
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 Stylastrea, 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 
strie 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 lamelle converging from the walls to- 
wards the flat central style or axis, which is about 1 line in 
width; one half of the lamelle reach the centre, the inter- 
vening ones reach half way; outer area exhibiting numerous 
transverse vesicular plates between the radiating lamelle : 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 obliquely 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 lamelle. 
From the carboniferous limestone of Derbyshire. — 
(Col. University of Cambridge.) 
