1 88 TABULATE CORALS. 



enchyma, however, exhibits very commonly small irregularly- 

 distributed and irregularly-shaped vacuities, which vary much 

 in number in different specimens, or even in different parts of 

 the same specimen. Sometimes they are almost wholly 

 absent, sometimes they are so far abundant that one may 

 count five or six in the wall surrounding one corallite ; while 

 they may be circular, oval, crescentic, or quite irregular in out- 

 line. They are seen both in transverse and vertical sections 

 (PI. IX., figs. 2 and 2 a), and they can often be detected 

 on the surface in the form of pits in the thick margins of 

 the calices. It would appear to have been the above structures 

 which induced M'Coy to place Lyopora favosa in the genus 

 Heliolites {PalcEOpoi'a) ; but microscopic sections prove, beyond 

 the shadow of a doubt, that they are certainly not " ccenen- 

 chymal " in their nature. They are either placed at the angles 

 of junction of the original corallites (when these can be detected 

 at all), or they run in the substance of the wall itself. It is 

 clear, therefore, that they cannot be " coenenchymal tubules ; " 

 but it is at the same time difficult to say precisely what they 

 are. Probably they are (as suggested by Mr R. Etheridge, 

 jun., and myself, loc. ciL, p. 28) mere vacuities due to imperfect 

 deposition of sclerenchyma ; but the more regularly-shaped 

 ones are possibly of the nature of the " intramural canals" of 

 Columnopora, whatever these may be. 



As regards the other features in the anatomy of Lyopora, I 

 have failed to find any evidence of the existence of " mural 

 pores," after a careful examination of a large number of speci- 

 mens and of microscopic sections. I am not, however, prepared 

 to assert that mural pores may not ultimately be proved to 

 be present. The septa are entirely rudimentary, and have the 

 form of broad, obtuse, and somewhat irregular marginal ridges, 

 which project to an extremely limited extent into the visceral 

 chamber (PI. IX., fig. 2). The tabulae are strong and complete, 

 and, in the only species known, are usually remote and hori- 

 zontal (PI. IX., fig. 2 a). 



