320 



Fig. 8. Six illustrations showing modifications of the lunarium. a. Fistulipora 

 astrica TJL; b, Crepipora simulans Ul.; c, Anoloteichia ponderosa UL; d, Cystodictya 

 occellata Ul., one of the zooecia divided horizontally just above the primitive orifice ; 

 e, vestibule of a cooecium of Cystodictya gilberti Meek, cut transversely just beneath 

 the external aperture; /, zooecium aperture of Buskopora. 



In the above cut, a, representing a tangential section of a 

 zooecium of Fistulipora astrica UL, shows the lunarium in its 

 normal form; b, shows the true "crescent" as it appears in 

 Crepipora and other Ceramoporids. Here the outer or convex 

 line of the crescent is sharply defined, the inner much fainter, 

 and the intermediate space filled with nearly transparent struc- 

 tureless substance; c, is apparently intermittent, or traversed 

 in a longitudinal direction by minute tubuli, which vertical 

 sections (pi. XLI, fig. 3c,) show to have been intersected by 

 numerous diaphragms - d, represents a zooecium of Cystodictya 

 just about to pass in the mature stage ; e, the cell just beneath 

 the external orifice. These show that the lunarium is not devel- 

 oped excepting in the vestibular portion of the zooecium. In 

 Buskopora (fig. f.) we see a decided modification. In this re- 

 markable genus the lunarium is formed by the channeling of an 

 internal ridge which projects far into the zooecial chamber. In 

 Cystodictya gilberti Meek, and Coscinium cribriformi Prout, (PI. 

 XLIII, fig. 7, 8) the crescent is also very prominent (especially 

 near the edge of the zoarium) but it is a much less separate 

 structure. 



IX. Wall inflections. Nothing that will compare with the 

 ' 'septa" of a coral, nor even the imperfect spiniform septa of 



