MADREPOEA. 79 



the corallites are shorter, often a little thickened, with a number of small immersed ones 

 interspersed. In some cases the under surface of the branchlets is almost devoid of corallites. 

 The star of the radial corallites consists usually of a narrow primary and a rudimentary 

 second series of septa ; but sometimes the directives are rather prominent. Corallum very 

 porous ; surface spongy reticulate and strongly echinulate ; wall strongly striate (fenestrated 

 at first), apparently not echinulate. 



? Indian Ocean. 



66. Madrepora tubigera. 



Madrepora tubigera, Horn, Proc. Acad. Nat. Sci. Philad. 1860, p. 435 ; Verrill, Bull. Mus. Comp. Zool. 

 ■ 1864, vol. i. p. 41 ; Studer, Mitth. naturf. Ges. Bern, 1880, p. 19 ; Quelch, ' Challenger ' Keof- 

 Corals, p. 161. 

 ? Madrepora capillaris, Quelch {non Klunzinger), 'Challenger' Reef-Corals, p. 161. 

 ? Madrepora durvillei, Fowler, Q. J. M. S. 1886, vol. xxvii. p. 1, pi. i. 



The following is Horn's description, which has not been extended by subsequent 

 observers : — 



"M. prostrata, ramis paulum diifusis, stricte ramosis ; ramulis attenuatis (base 3'"), apice 

 acutis. Corallum porosum, caliculo apicale elongato, cylindrico (3-4"' ssepe 5'" longo et #"' 

 lato) ; lateralibus tubiformibus ssepe labellatis et dimidiatis ; stella conspicua." 



The specimens referred by Quelch to this species have the following characters : 



Corallum extending obliquely or suberect, much branched. Main branch 1'5 cm. thick • 

 branchlets 1-3 to 3'5 cm. long and 3 to 6 mm. thick; some are simple, but the majority 

 are bi- or trifid near the base. The more slender ones consist of a much elongate and often 

 curved tubular corallite 8 to 14 mm. long and 2 mm. thick, which bears a few small fragile and 

 distant buds. The axial corallites of the stouter divisions are also 2 mm. diameter but are 

 rarely more than 2 or 3 mm. exsert. The radial corallites are usually appressed, labellate, or 

 nariform, passing below into short tubular ones (with the outer part of the wall a little 

 prolonged) and finally immersed ; the more prominent ones are 4 mm. long, ratlier narrow 

 and appressed near the base, but the lip is much broader and recurved, 2 mm. across the 

 widest part; the length and breadth of the corallites varies with the thickness of the 

 branchlet. The tubular ones near the base of the colony are 2 mm. diameter and 1 to 3 mm. 

 long ; the immersed ones are a little smaller. In all the radial corallites, excepting perhaps near 

 the base of the stouter divisions, the wall is very thin and fragile. In the axial corallites the 

 star consists of two well-developed cycles of septa ; in the radial corallites the directive septa 

 often fuse together in the middle line ; the other primaries are moderately developed, but 

 the second cycle is usually not noticeable. Corallum extremely porous and reticulate in 

 section ; surface reticulate and echinulate. The wall of the elongate tubular corallites is 

 costulate ; the costse become echinulate in the lower part of the corallite. The others are 

 costulate and echinulate, but the striations become lost near the base of the corallum. 



The fragments referred by Quelch to M. capillaris, Klz., probably do not belong to that 



m2 



