MATTHAI— RECENT COLONIAL ASTR^ID^ 55 



Corallum. All the variations in growth-form of the genus. Peritheca usually- 

 vesicular, vpalls of vesicles about '75 mm. apart, with distinct ridges connecting neighbour- 

 ing costse ; spines present or absent. Corallites usually circular, projecting in different 

 directions, vertical, oblique, or quite horizontal, up to 6 mm., usually about 3 mm., 

 increasing in diameter from margins to bases, up to 6 mm. apart, average 2 or 2"5 mm. 

 Calices with diameter up to 7 mm., depth 2 mm. . 



Septa in four orders, up to 18 quaternaries, sides spinulate, edges denticulate. 

 Primaries sometimes thicker than secondaries, these and uj) to 8 tertiaries meeting 

 columella. Primaries and secondaries with their outer halves usually twice or thrice the 

 thickness of the inner halves, dipping down vertically till level of columella, then thinning 

 out and passing horizontally inwards to meet columella, exsert to 1 mm., the exsert end 

 of each often divided by a notch over corallite-wall into a somewhat larger inner lobe and 

 a smaller outer lobe, sometimes arched, not divided. Pali less than 12, about 6 or 

 altogether absent. Septa perforated, the gaps in edges often leaving long, slender 

 processes which in some corallites form fenestras over the axial fossse. Those tertiaries not 

 meeting columella usually curve towards and fuse with sides of secondaries, quaternaries 

 also with tertiaries. Costse usually low flat ridges with spinulate, blunt, upright 

 echinulations, varying in height and degree of roughness and presenting an appearance 

 of large and small ridges as the costae of the last cycle are much less conspicuous, the 

 latter sometimes absent. Columella formed of loosely twisted trabeculae, about one-third 

 width of calyx. 



Polyps. (1) A few tertiary couples of mesenteries present, the cycle being never 

 complete. (2) Directive grooves not deep. (3) Nematocysts I more numerous in 

 ectoderm of oral-disc and outer wall of edge-zone than in E. hirsutissima, but less 

 abundant in lower halves of stomodseal ridges and in straight regions of mesenterial 

 filaments than in that species. (4) Entocoelic pleats in stomodaeal region of polyps 

 obliquely directed towards stomodseum, narrower than in E. hirsutissima, and not 

 extending beyond the outer halves of primary mesenteries, usually restricted to their 

 outer one-third ; pleatal region much thicker than non-pleatal region ; no exocoelic pleats. 

 (5) Mesenterial endoderm thicker near stomodseal attachrdents than elsewhere. (6) En- 

 doderm in outer wall of edge-zone two-thirds the thickness of the ectoderm over it, 

 much thinner in oral-disc. (7) Convolutions of mesenteries scarce towards bases of 

 polyps. 



Remarks. A. Polyps. These are circular in outline about 3 "5 mm. in diameter. 

 Tentacles are not present over the tertiary entocoeles, and only a few exocoelic tentacles 

 are present; as all the tentacles were in a retracted condition exact counting of the 

 sub-terminal batteries was impossible.. The stomodaeum is 1"35 mm. long by "75 mm. 

 broad ; one directive groove is better developed than the other ; the ridges are 

 narrower than in E. hirsutissima. In the three polyps examined 2, 3, and 6 couples of 

 tertiary mesenteries are present. 



The ectoderm of the oral-disc and of the outer wall of the edge-zone are somewhat 

 thicker than in E. hirsutissima, with abundant mucous vacuoles. In most of the 

 nematocysts III 6 the coiled thread is partially extruded; the dark-stained axis of II 



