40 MADEEPOEARIA. 



16. Madrepora arbuscula. 



Madrepora arbtisntla, Dana, Zoophytes, p. 474, pi. xl. fig. 2 ; M.-Edwards & Haime, Coralliaires, t. iii. 

 p. 138 ; Verrill, Proc. Essex Inst. 1866, vol. v. p. 21 ; ? ibid. 1869, vol. vi. p. 69 ; Verrill, BuU. 

 Mus. Comp. Zool. 1864, vol. i. p. 41 ; Studer, Mitth. naturf. Ges. Bern, 1880, p. 19 ; Eathbun, 

 Proc. U.S. Nat. Mus. 1887, vol. x. p. 12; Ortmann, Zool. JB. 1888, Bd. iii. p. 149. 



? Madrepora scabrosa, ? B.-Smith (non Quelch), Ann. Mag. N". H. 1890, vol. vi. p. 452. 



Corallum arborescent, much branched, forming bushy clumps 30 cm. high and 40 cm. in 

 diameter from a stem 2 cm. thick. Branches spreading, terete, 8 to 18 mm. diameter, only 

 slightly tapering. Upper branches often 8 to 11 cm. long, simple and very gradually 

 attenuate. Axial corallites 2*5 to 3 mm. diameter and 25 mm. exsert, wall thick and porous. 

 Radial corallites 1'5 mm. diameter and 3 to 4 mm. long, tubular, more or less ascending, and 

 with a moderately thick wall ; crowded on the superior surface, but more distant on the 

 underside, becoming short and thick tubercles on the under surface of the stouter branches. 

 Corallum porous and fenestrated in section, surface finely reticulate and echinulate ; wall 

 striato-reticulate whien thin, becoming evenly echinulate with increase in thickness. All the 

 primary septa are broad, the directives nearly meet in the middle line ; second cycle 

 inconspicuous. 



Indo-Pacific Ocean : Singapore, Sulu Sea, ? Japan, Great-Barrier Reef. 



a. ? Mr. Sowerby [P.]. 45.5.21.135. 



b. ? Purchased. 59.12.12.1. 



c. ? ? 93. 4. 7. 86. 



d,c. Palm Island. Saville-Kent Coll. 92. 6. 8. 73 & 74. 



/. Channel Rock Reef. Saville-Kent Coll. 92. 6. 8. 79. 

 ?ff. Tizard Bank. H.M.S. ' Rambler.' 89. 9. 24. 110. { = M. scabrosa?, B.-Sm.) 



17. Madrepora virgata. 



Madrepora virgata, Dana, Zoophytes, p. 471, pi. xxxix. fig. 1 ; M.-Edwards & Haime, Coralliaires, t. iii. 

 p. 145 ; Verrill, Bull. Mus. Comp. Zool. 1864, vol. i. p. 41 ; Studer, MB. Akad. Wiss. Berlin, 

 1878, p. 533; Quelch, ' Challenger ' Ileef Corals, p. 158; Eathbun, Proc. U.S. Nat. Mus. 1887, 

 vol. X. p. 19. 



Madrepora gracilis, Quelch, ' Challenger ' Reef Corals, p. 158 (part.). 



Corallum slender, arborescent, spreading and remotely ramose; branches under 1 cm. 

 in diameter, very long, terete, subarcuate, not proliferous. Coenenchyma scarcely porous, 

 minutely granulous ; radial corallites small, rather crowded, very short and thin tubular ; 

 margin acute, cell circular, star of six narrow rays. Terminal branches often 15 cm. long, 

 very gradually tapering. 



The above is a summary of Dana's description : the ' Challenger ' specimens referred 

 by Qaelch to thia species differ in several important points. The coenenchyma is very 

 porous and reticulate in section, the surface is covered with closely-placed rows of dentate 



