88 



PALEOZOIC CORALS AND FORAMINIFERA. 



tion, radiating lamellse forty-eiglit, thin, twenty-four of which 

 reach the centre, while the intervening ones are nearly mar- 

 ginal, not reaching half-way to the inner zone ; interlamellar 

 vesicular plates very numerous and delicate in the outer zone, 

 apparently absent in the inner zone. 



This species has some affinity with the N. minus (M'Coy), but 

 is constantly distinguished by the open, simple, subseptate cha- 

 racter of the inner zone in the vertical section, the extreme com- 

 parative shortness of the alternate lamellae in the transverse sec- 

 tion, and the peculiar character of the broad, simple, cup-like 

 plates of the inner zone in the rough transverse fracture. 



Very common in the carboniferous limestone of Tullyard, 

 Armagh, Ireland. 



[Col. University of Cambridge.) 



Stylaxis (M'Coy), n. g. 



Gen. Char. Corallum composed of adjacent polygonal, prismatic, 

 easily separable tubes, inter- 

 nally divided into three areas : 

 vertical section, 1st, a thin, flat, 

 straight axis ; 2nd, a broad in- 

 ner area composed of nume- 

 rous curved vesicular plates in 

 irregular rows converging up- 

 wards to the axis ; 3rd, an outer 

 area on each side composed of 

 smaller and more curved vesi- 

 cular plates, in rows inclining 

 obliquely upwards and out- 

 wards : horizontal section dis- 

 playing the central flat axis 

 surrounded by radiating la- «• Mode of growth and division of 

 mell^ extending from the walls, ^^tem ; 6 horizontal section; 



J i. J • i-i J. c. vertical section. 



and connected in the outer area 



by numerous transverse vesicular plates : additional columns 

 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 Stylastrcea (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 



