MATTHAI— RECENT COLONIAL ASTR^ID^ 61 



ectoderm of the outer wall of the edge-zone. The ectoderm of the oral-disc is thick with 

 nuclei massed together in its lower half, ovoid bodies rare, nematocysts I and 116 frequently 

 present. In the upper half of the ectoderm of the outer wall of the edge-zone nuclei are 

 arranged in layers with numerous mucous vacuoles and nematocysts I and II. In the 

 terminal batteries, nematocysts II b are more numerous than I, the latter with up to 

 30 turns of the spiral. Ovoid bodies absent, but present in the sub-terminal batteries. 

 Mucous vacuoles stain orange with heematoxylin and eosin as in Leptastrea roissyana, 

 Ed. and H., in contrast to species where the colour is brown. The stomodseal ridges are 

 as broad as or broader than thick, nuclei massed together towards the lumen and ovoid 

 bodies towards the mesoglgea ; nematocysts absent. Filaments are well developed on 

 primary and secondary mesenteries, rudimentary on rest; nematocysts are scarce in their 

 straight regions, but I and II occur in small numbers in the coils. The mesenterial 

 mesoglsea thickens near the stomodseum, on this part exocoelic fibres being better 

 developed. The endoderm in the oral-disc and in the body-wall above the enterostome is 

 thin, and contains a few algse ; it is much thickened in the outer wall of the edge-zone, 

 thin in its inner wall ; in the tentacles it is as thick as the ectoderm of the sub-terminal 

 batteries, and algae are more abundant in the entocoelic than in the exocoelic tentacles ; 

 over the mesenteries the endoderm is comparatively thin, except near the stomodfeal 

 attachments of the primaries. 



Gonads were not present in the polyps examined. 



Polyps examined, three ; from two colonies from the Red Sea. One of these was a 

 young polyp 4 mm. in height and 2 mm. in diameter, in which only four tertiary couples 

 had appeared. 



B. Corallum. The corallum of this species is apparently very variable. Most of the 

 examples of G. irregularis, Ed. and H., that I have examined differ from my specimen, 

 whose polyps were sectioned in having larger corallites, which are laterally compressed or 

 distorted. The appearance suggests that the large size and the distortion might be due to 

 a somewhat retarded fission, but, of course,- this can be ascertained only by an examination 

 of the polyps. 



The specimens referred by Prof. Gardiner to G. fascicularis form a somewhat hetero- 

 geneous lot, one of them approaching G. musicalis in appearance. They differ from the 

 specimen on PL 16, fig 4, in the following respects : (l) primary and secondary septa of almost 

 equal thickness and more highly exsert, up to 4 mm. ; (2) primaries swollen in thecae but 

 thinner in calicos ; (3) costse more prominent ; (4) columella better developed ; 

 (5) corallites often irregularly compressed, tending to be sub-triangular in outline and 

 with thicker walls. In other words, they have more or less the n'regidaris facies. 



Milne Edwards and Haime have referred nine specimens in the Paris Museum to 

 G. fascicularis, of which four are in Lamarck's collection, and four others to G. irregularis; 

 an example of each of these species resembles my figured specimen. The same authors 

 have assigned three specimens to G. ellisi; the same name is written on four specimens of 

 Rousseau's and one of Agassiz's. 



Of the four examples in the Berlin Museum named Anthophyllum fasciculare by 

 Ehrenberg, No. 624 (12x7 cm., PI. 38, fig. 6) is identical with my figured example ; the 



