to Micro-Palceontology. 287 
their course the corallites assume their mature characters, and 
now exhibit the features peculiar to Stenopora. As regards 
their direction, they are now bent outwards approximately at 
right angles to the axis of the branch, and their walls are now 
thickened periodically by annular enlargements, which are 
placed at corresponding levels in contiguous tubes. Hence, 
in the broken ends of the branches, the corallites show a 
highly characteristic beaded appearance ; and in thin sections 
(fig. 1, C) the walls are seen to have a marked moniliform 
structure, narrow unthickened segments alternating with 
annular thickenings or nodes. 
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Stenopora Howsw, Nich., from the Carboniferous rocks of Redes- 
dale. A. Tangential section traversing in part the unthickened 
segments of the tubes. B. Tangential section traversing the thickened 
segments of the tubes. C. Portion of the peripheral region of a transverse 
section, showing the thickenings of the walls and the perforated tabule, 
All the figures are enlarged about eighteen times, 
As regards the minute structure of the walls of the corallites, 
the thickened nodes are formed (as in the species of Stenopora 
generally) by the growth of successively superimposed thin 
layers of sclerenchyma, each layer forming a kind of conical 
cap, as seen in section (Pl. X. fig. 10). The walls of adja- 
cent corallites are apparently so amalgamated and fused 
together that no traces can, as a rule, be detected of the 
original boundary-lines of the separate tubes. In some cases, 
however, in tangential sections it is possible, by means of a 
careful management of the light, to recognize the original 
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