﻿GLABROUS MONTIPORiE. 37 



20. Montipora spongodes. (PI. III. figs. 2 and 3 ; PI. XXXI. fig. 16.) 



Description. — Corallum encrusting, creeping down round former growths, but also rising up 

 into solid shapeless masses, jagged or even branched, the branches being smooth. The masses 

 light, like pieces of pumice stone. 



Calicles small, under 1 mm., evenly distributed, generally rather wide apart. Parts of 

 two cycles of septa formed by free ends of the reticulum of the coenenchyma. Septa always 

 thinner than the threads composing the reticulum, those of the second cycle much finer than 

 those of the first. 



Coenenchyma evenly reticular throughout, superficially resembling the texture of the bath 

 sponge. 



The above description applies to a group of specimens all showing the same general 

 characters, but of many different shapes. 



a. Providence Island, Mascarenes H.M.S. 'Alert.' [82. 10. 17. 194.] 



(coral bottom, 19 fathoms). 



In this specimen (a) the coral has almost completely invested some irregular foreign body, 

 perhaps a previous growth. On the one side it has grown out into a soKd mass terminating in 

 irregular branches which tend to rise, and on the other it has sent out a free expanding layer, 

 with calicles on both sides, which, instead of rising, has drooped and seems to have touched the 

 substratum at many points. 



The calicles are small, but are visible as faint whitish rings just raised above the 

 ccenenchyma or on the explanate portions as slight mounds, the apertures themselves being 

 barely visible. They are not crowded, being some 2 mm. at most apart. The first cycle of 

 septa nearly close the fossa ; those of the second cycle, which appear in the larger calicles, are 

 very fine. 



The reticulum on the upper surface is rather close and flaky, the free ends forming short 

 echinulffi ; on the under surface it is more open and thread-like, and the echinulse are long 

 and conspicuous. 



b. Original label detached, but probably from H.M.S. 'Alert.' [97. 6. 18. 5.] 



same locality as a. 



The corallum in this specimen (&) is a thick shapeless mass, the upper surface of which 

 runs out into irregular conical points. It appears to be largely hollow, and to have arisen by 

 a thin growth hanging down more or less freely over a previous growth of the same coral, the 

 under surface being followed by an epitheca and the lowest growing and pendent edge being 

 about 3 mm. thick. This is the specimen figured on PI. III. fig. 2. 



The calicles are evenly distributed but much further apart than in a, and there is not the 

 same tendency to rise above the surface. The two cycles of septa irregularly but more 

 equally developed, i.e. there is not the same marked difference in development between the 

 first and second cycles. A well developed, deep, cylindrical fossa renders them conspicuous 



