The individual are quite smal] dome-shaped verrucae when the polyps are 



ted, and short tubes when they are completely expanded. They are so closely 



.■il the surfaces of the branches as to 1"- contiguous al their bases. A typical one 



mi mm. in diameter .11 the base. f/he height varies in accordance with the state ol 



of the polyps, but seldom exceeds i mm. The calyx walls are armed with very 



i spindles and Blattkeulen and, in certain stages of contraction of the polyps, the margin 



distinctly 8-lobed. The polyps have a rather slender collaret, above which the spindles form 



dit points. Beyond these points there are a few longitudinal spindles, lying along the dorsal 



•f the tenl Minute spindles also extend from the dorsal surfaces diagonally t" 



the pinnule bas< s. 



Spicules. The most characteristic forms are remarkable Blattkeulen which consist of 

 .1 tuberculate base from which project a number of parallel flattened finger-like points. Or they 

 may be likened to a plate which has been shattered by several vertical fissures. There is 

 nplete intergradation between these Blattkeulen and typical Stachelkeulen, so that it is hard 

 to differentiate them. Besides tliese curious forms there are regular spindles often curved, from 

 the polyps, and clubs, besides a greal variety of nondescript forms. 



lor. The colony is a rather tlull yellowish brown. The spicules are colorless. 



;. Mopsella spongiosa new species. (Plate YIII. figs. i, ia, Plate XII, fig. 7). 



Stat. 273. Anchorage off 1'ulu Jedan, East coast of Aru Islands (Pearl Banks). [3 nieters. 

 Sand and shells. 



lony strictly llabellate and reticulate, spongy in texture and not so delicately branched 

 in the other species, although the meshes are fine. Height of colony 21.5 cm. Spread 20 cm. 

 The main stem is irregular in section, but not appreciably flattened, and is 14 mm. in diameter. 

 About [8 mm. from its base it breaks up into numerous branches which redivide to make the 

 mesh. In the main stem the nodes and internodes are hardly distinguishable. In one of the 

 main branches the proximal node is j.^, mm. long and 5 mm. in diameter, while the proximal 

 internode is 2.3 mm. long and 3 mm. in diameter. The nodes are much swollen and longer 

 than the internodes throughout the basal parts of the colony. A node near the edge of the 

 fan is 4 mm. long. while the internode just below it is 11 mm. long and 1.0 mm. in diameter. 

 Most of the branches are somewhat flattened, but the distal twigs are round. The meshes are 

 small, usually oblong, and the anastomoses are usually, but not always, at the nodes. The 

 are emplanted very thickly on these sides of the main branches and on all sides of 

 the distal ones. 



Spicules. The most typical form of spicule in this species is the foliaceous club, with 

 an irregular densely tuberculate basal part and a distal portion consisting of several flattened 



ions usually extending parallel to each other and often in the same plane. Frequently 

 tin the form of coarsely tuberculate spindles from one side of which the foliaceous 



ons arise, making "unilateral" spindles. These Blattkeulen are exceedingly varied in 



