MADEEPOKA. 93 



Madrepora microdados, Studer, MB. Akad. Wiss. Berlin, 1878, p. 526; Studer, Mitth. naturf. Ges- 

 Bern, 1880, p. 20 ; ? Ortmann, Zool, JB. 1888, Bd. iii. p. 153 (non Bruggemann, Phil. Trans. 

 1879, vol. clxviii. p. 576). 



Madrepora cytherea, B.-8mith, Ann. Mag. N. H. 1890, vol. vi. p. 454. 



? Madrepora effiorescens, B.-Smith {non Dana), Ann. Mag. N. H. 1890, vol. vi. p. 454. 



Corallum broad and shallow vasiform or tabulate, usually 3 to 2-5 cm thick, but 

 occasionally 5 cm. Under surface complanate and closely reticulate, the branches frequently 

 laterally compressed, about 1*2 cm. by 7 or 8 mm., usually devoid of branchlets. Corallites 

 usually immersed, with a variable number of short appressed tubular corallites, sometimes 

 only near the margin of the colony, at others scattered over the whole surface. In some 

 specimens, which agree in other respects, the immersed corallites of the under surface are 

 almost entirely replaced by appressed and dilated corallites with small aperture. Branchlets 

 on the upper surface numerous, subequal, erect, rarely proliferous near the apex, but often 

 furcate below, apices about 8 mm. apart ; length usually 8 to 12 mm., diameter 4 to 5 mm., 

 subterete and more or less distinctly tapering. Axial corallites 1"5 mm. diameter, 0'5 mm. 

 exsert ; wall not much thickened. Radial corallites immersed or subimmersed on the upper 

 surface of the branches and at the base of the branchlets, becoming flattened labellate, and 

 imbricate nearer the apex, about 2 mm. long and the lip r5 mm. broad; wall thin; in some 

 specimens the lip is not flattened and the corallites are rather more distant. Star rarely 

 distinct, but the directive septa are more or less prominent. Corallum porous ; surface 

 reticulate and echinulate ; wall striate and more or less distinctly echinulate. 



Var. abhreviata. 



Habit of the type : branchlets 6 to 25 mm. long, obtuse at the apex, with scarcely 

 prominent axial corallites ; radial corallites much shorter and more closely crowded. {Dana.) 



Var. eucladia. 



Resembles the type form, but the under surface of the frond is covered with stout 

 obsolescent corallites, which are rather crowded and render the surface uneven. Branchlets 

 18 mm. long and 3 to 4 mm. diameter, 6 mm. apart, regularly tapering and subacute, 

 crowdedly covered with small thin corallites. {Dana.) 



The small Fiji specimen figured by Dana does not represent the habit and appearance 

 of the species, and it is probable, as hinted by Dana in the text, that the specimen does not 

 belong to this species. I have referred it to M. armata. 



Var. sinensis ( = M. spicifera, var. abbreviata, and M. cytherea and ? M. effiorescens, 



B.-Smith). 



Several specimens from the Tizard Bank present a general resemblance to this species, 

 but may prove to be specifically distinct. The specimens vary considerably in appearance, 

 but all seem to me to be variations of one form. CoraUum shallow, half-vasiform, 44 cm. 

 wide and usually under 2 cm. thick. Under surface closely reticulate, sometimes with a few 

 incipient branchlets, chiefly in the general plane. Corallites on the iinder surface short, 



