768 J- STANLEY GARDINER. 



The septa, where they pass into the theca, are often quite hollow. The endothecal 

 dissepiments, distant I'S to 2 mm., commonly e.\tend downwards from t^e theca at an angle 

 of about 4.5°. All parts tend to be excessively thin and delicate, though the hollow, rough 

 nature of the septa, together with their small number in the large calices, gives the species 

 a coarser and more open appearance than any other in the collection. It differs in the vesicular 

 exotheca (difficult generally to distinguish, chambers about 1 mm. high) from F. cavernosa, 

 the possible variation of which in most other points might well cover it. Its form of growth 

 is bigger but otherwi.se closely related to F. denticulata. 



Locality. Hulule, W. reef (calices slightly smaller than in the other specimens, distinct 

 furrow, septa less exsert but thicker edged, paliform lobes less marked), Minikoi, lagoon shoal 

 (very light and of most vigorous growth) and a doubtful fragment from the reef-flat. 



24. Favia denticulata (Ell. and Sol.). (PI. LXI. figs. 14—18.) 



Madrepora denticulata. Ell. and Sol, Zooph. p. 166, pi. 49, fig. 1 (1786), Favia 

 denticulata, Ed. and H., ii. p. 428 (non Astraea denticulata, Dana, p. 234, 1846, Gard., 

 p. 748), Favia denticulata, Klz., p. 27, 1879. ? .syn. F. urvilleana, F. doreyensis, 

 F. geoffroyi, F. aspera, all Ed. and H. 



The characters of this extraordinarily variable species are as follows : Colonies very 

 markedly massive in growth, closely incrusting at edges with a quite determinate, transversely 

 marked epitheca. Walls always with upper edges of theca distinct and slightly raised above 

 the top dissepiments, 2 to 4 mm. thick. Calices always rounded, elongated, or a little distorted 

 where dividing, often somewhat oval, average size varying from 6 to 10 mm. in diameter and 

 2 to 6 mm. in depth. Costae commonly continuous between calices, always sloping below level 

 of top of theca (hence very distinctly furrowed appearance, or series of notches on the walls), 

 and equal in number to the septa, but sometimes additional ones marked by fine linear ridges 

 or lines of granules or spinules (especially where septa are less numerous). Septa always 

 somewhat exsert ('.5 to 25 mm.), always arched above, upper end almost horizontal, 20 to 40 

 (generally 24 to 34) in number, no distinct cycles, outer halves almost perpendicular, closely 

 set with small, fine, subequal teeth, commonly on 10 to 20 of the larger septa passing below 

 into 1 or more upstanding paliform lobes, or at least ending perpendicularly against the 

 axial fossa. Columella ^ to ^ breadth of calice, flat-topped, spongy, formed by very fine, much 

 twisted trabeculae from the 10 to 20 larger septa. In section exothecal dissepiments 1 mm. 

 apart, horizontal, endothecal same, often rather oblique to 50°. 



It will be obvious even from the above description that the corallum varies extraordinarily 

 in external appearance, a form with calices averaging 10 mm. in diameter by 5 — 6 in depth, 

 with marked furrows, thick, rough septa with broad, paliform lobes, superficially having little 

 resemblance to one averaging 7 mm. by 3 mm., no furrows, thin, smooth septa and little 

 or no paliform lobes. Yet all are clearly joined by their distinct, never angular nor gyrose 

 calices, thick walls with larger or smaller furrows above, septa arched and of similar shape, 

 mode 25 to 29, and spongy columella. In my specimens all other characters show variation, 

 a little in each colony but in most characters far. more in the series. Any one character 

 may become definitely fixed in any locality in any type of the series and give a definite 

 species. I affix a name and a list of s;yTionyms, but I recognise my temerity in so doing 

 partly for the above-mentioned reason, and partly because the descriptions commonly given 

 by older authors were quite inadequate, often from single specimens or fi'om unknown 

 localities. 



