52 PERCY SLADEN TRUST EXPEDITION 



1816. Explanaria geiriTnacea, var. stellis comosis, Lamarck, Hist. Anim. sans vert., ii, p. 256; 2'^ edit., p. 399. 



1 1848. Echinopora ringens, Dana, Expl. exp. Zooph., p. 279. 



1850. Echinopora rosulwria (pars), Milne Edwards and Haime, Ann. Sci. Nat., Zool., 3<^ ser., xii, p. 185. 



1850. Echinopora hirsutissima, Milne Edwards and Haime, Ann. Sci. Nat., Zool., 3"= ser., xii, p. 187. 



1854. Echinopora helli, Louis Rousseau, Voy. p61e sud Dumont-d'Urville, Zool., v, p. 120, Zooph., pi. 27, 



fig. 3. 

 1857. Echinopora helli, Milne Edwards and Haime, Hist. nat. CoralL, ii, p. 623. 

 1857. Echinopora rosularia (pars), Milne Edwards and Haime, Hist. Nat. CoralL, ii, p. 623. 

 1857. Echinopora hirsutissima, Milne Edwards and Haime, Hist. Nat. CoralL, ii, p. 624. 

 1904. Echinopora solidior, Gardiner, Fauna Geogr. Maldives and Laccadives, p. 782, pi. 63, fig. 38 (non 



Echinopora solidior, Milne Edwards and Haime). 

 1904. Echinopora tertia, Gardiner, Fauna Geogr. Maldives and Laccadives, p. 782, pi. 63, fig. 39. 



Corallum. Incrusting, relatively thin, much coarser than in E. Icumellosa, edges 

 usually somewhat folded over, free only at edges. Peritheca dense, with upright blunt 

 spinulate echinulations up to 1 mm. in height, bases of spines sometimes united to form 

 ridges especially seen towards edges. Corallites oval, sometimes circular, level with 

 general surface to 1 mm. high, touching or up to 4 mm. apart, usually 2 or 3 mm. Calices 

 up to 8 mm. in diameter, average 5"5 — 6'5x4'5 — 5 mm., depth 2 mm. 



Septa in four orders, the fourth incomplete, comparatively broader than in 

 E. lamellosa, sides spinulate, edges denticulate. Primaries thicker than secondaries ; 

 both these and a varying number of tertiaries — up to 8 — with their outer half or a 

 little more thicker, from 5 — 7"5 mm., dipping down vertically till level of columella, 

 then thinning out and extending horizontally inwards to meet the latter, around 

 which is a ring of about 12 spinulate pali each 1"5 mm. high. Septa meeting columella 

 exsert to 1"5 mm., exsert end divided over the calicular margin by a deep notch into an 

 inner lobe about 1 mm. broad and an outer narrower lobe, the latter sometimes appearing 

 as the first costal tooth. Septa often perforated behind pali, hence the latter appearing 

 connected by slender rods to the septal margins. The tertiaries not meeting columella 

 curve towards and fuse with sides of secondaries near to columella. Quaternaries very 

 narrow and thin, up to 14 in number. Costse of primaries to tertiaries with 1 — 3 con- 

 spicuous blunt upright spinulate echinulations, those of quaternaries thin and inconspicuous. 

 Columella about one-third width of calyx or slightly more. 



The corallum of this species is very variable. E. tertia, Gard. (PL 15, fig. 3 and 

 17, fig- l) with identical polyp-structure as E. hirsutissima is only a skeletal variety, 

 differing from it in the following respects : — (1) corallites projecting up to 2 mm., some- 

 what further apart ; (2) costal and perithecal spines thinner and shorter, in places not 

 regularly arranged ; (8) septa less exsert, thinner and more perforated, the gaps often 

 seen in the edges leaving slender irregular processes which tend to intercross over the 

 axial fossae ; (4) columella somewhat less than one-third width of calyx and formed 

 of looser trabeculae. Another specimen with similar polyp-structure resembles E. lamellosa 

 (PI. 14, fig. 7) in skeletal characters more than E. hirsutissima — slender shorter 

 perithecal spines, corallites more exsert (to 2 mm.), calices circular and smaller, septa 

 thinner, columella half width of calyx — but has a greater number of quaternaries, 

 up to 14 as in E. hirsutissima, and a ring of about 12 pali not rising above calicular 

 margin. 



