ASTR.'EOPOR/E PULVINAT^. 93 



and regularly developed, the former being somewhat more pronounced. Sections further show 

 a regular tapering of the costal vertical elements : as they slope away from the walls of the 

 calicles they are tliick, but get thinner and thinner, eventually ending as thin pillars to the 

 floors in the interstices. 



As is typical in this method of growth, the lengthening calicles develop tabulae at 

 irregular intervals, from 1 to 2 mm. apart. 



There is a single specimen of this coral, a fragment, but fortunately large enough to 

 reveal unmistakably the method of growth. It was one of Dr. Klunzinger's collection, and 

 was named by him Adravpora myrioiMlialma, Lamarck. Judging, however, from this frag- 

 ment, and from Dr. Klunzinger's description, it belongs to the pulvinate, not to the explanate, 

 division. The great, smooth, rounded top, with downward growing edges, the great length of 

 the calicles and regular increase in thickness of the ca-ncnchyma confirm this view, and 

 remove the species entirely from myriophthalma, with its plate-like corallum, with its edges 

 often extending freely outwards, and its humpy, irregular surface. However well these 

 specimens seem to agree with Lamarck's description of myriophthalma when seen entirely 

 alone, when compared with a number of different forms they have to give place before others 

 which agree still more closely with the original description. 



This type might almost have been named after the exquisitely delicate and regular 

 texture of its ccenenchyma, as seen in section. I have named it after Ehrenberg, with whose 

 species rhyllopom (in two varieties, sphwrostoma and Icptostoma) Dr. Klunzinger, who had 

 access to Ehrenberg's types, has identified it. 



Dr. Klunzinger described these corals, when living, as being conspicuous, even from a 

 distance, by their brdliant greenish-yellow colouring. 



a Koseir -I ^^'""^ ^^^ I^^^^^^^g^"^'^ coUection 1 ^g^ ^^ ^ 33^ ^^ype.) 



I as A. myriophthalma, Lam. 1 



Species 8. Astrsopora gracilis. (I'l. XXIX. ; PI. XXXIII. fig. 14) 



Description.— (^oinMum showing pulvinate method of growth, tlie expanding top like a 

 thin encrusting layer, the edges of which may be restrained by an epithecal fold. 



The calicles small, well defined, circular (125 mm.), opening on solid-looking papillar 

 projections (sometimes 3 mm. high), very irregularly distributed, facing in all directions, 

 crowded and confluent, or with deep valleys between. The margin of the aperture is 

 granular, showing indication of the septa which, however, are hardly visible,'until deep down in 

 the fossa the six primaries project, as thin irregular plates, which do not meet in the centre. 



Young calicles, in all stages of development, in the valleys. 



Ccenenchyma. The whole surface of the corallum is very uneven, owing to the irregular 

 groupings of the prominent calicles and the varying dejiths of the intervening valleys ; but 

 it is evenly covered in all parts by echinuhB, crowded, short, longitudiuiUly striated, truncated 

 at the top, but sending up a few fine points ; these are thicker on the calicles than in the 

 valleys. A thin, porous, horizontal floor is visible in the valleys. 



