7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 31 



which the branch was broken off, is covered with asymmetrical calices. The 

 coenosarc of a young branch has a manifest tendency to fuse with that of any 

 other part of the colony with which it comes into contact. 



Gravier( 2 ) describes colonies of Siderastrea radians and siderea from Bella 

 Vista, St- Thomas (Gulf of Guinea) where they live in cavities in the beach, 

 excavated by burrowing crustaceans, although at changes of tide the water in 

 these cavities becomes muddy. In the upper part of the colony the calices 

 are contiguous, variable and irregular in form, narrowed (so as to reduce to a 

 minimum the access of the mud to the interior of the polyp) and deep. They 

 multiply actively by budding and fission. In the lower parts of the colony, 

 which are protected by their situation against the deposition of solid particles 

 upon them, or in colonies living under better conditions, the calices are wide, 

 polygonal, shallower and their septa are thicker. S. radians appears to be 

 the better adapted for life in muddy water but neither species attains its full 

 size except in the clear water of the reefs, on the muddy beach the colonies 

 are much smaller and on many of them dead areas, due to silting up, are 

 seen. See also Nordgaard. 



Verrill^) describes cases of regeneration in a cornucopia-shaped simple 

 deep-sea coral Parasmilia (now Desmosmilia) lymani. The walls of the coral 

 are very thin and fragile while the radial septa are strong so that, when in- 

 jured, the coral readily splits lengthwise into wedge-shaped fragments (entire 

 adult specimens are rarely taken) ; each fragment has the power of producing 

 one or more buds, on its inner surface, from the tissues covering the septa. 

 The single bud starts near the distal edge of a large fragment; it blends on 

 the outer side with the wall and septa of the fragment so as to sometimes 

 appear as if mere repair, with regulation of parts, had taken place. But when 

 the bud starts farther from the edge of the fragment it may grow up verti- 

 cally from it using the fragment only as a base of attachment. As many as 

 6 or 8 buds may arise from the inner surface of a large fragment and grow 

 up vertically or obliquely. This coral therefore presents gradual transitions 

 from the mere repair of an injury to the border of the calicle, or regeneration 

 of parts, to complete and perfect buds. See also Verrill( 2 ). 



Jones noticed inconstancy in the rate of growth of corals at Keeling-Cocos 

 atoll, temporary phases of activity alternating with phases of entire cessation 

 of growth. Observations which extend only over short intervals are therefore 

 of little value. In about 100 days massive forms increase on an average 

 1 / 37 th of their circumference and branching forms grow 2,74 cm. 



Crossland concludes that the coast of the Sudan, besides its major elevations 

 amounting to more than 1100 feet, has recently undergone several small 

 elevations, the movements having been uniform in their action and not recently 

 reversed. The differences between this elevated coral rock and rock of similar 

 origin elsewhere, e.g. on the coast of Equatorial East Africa, are due mainly 

 to the absence of tide and rain in the Red Sea. The present form of the 

 reefs is due as much to the eroding action of the sea upon this elevated rock 

 as to the growth of corals. In the case of fringing reefs the land is cut down 

 to sea level behind the rim of growing coral. Barrier reefs are formed (1) 

 by the direct growth of coral upon submarine hill ranges, the northern ends 

 of these have been elevated and are now ranges of coral-capped hills, the 

 middle parts remain as peninsulas and islands, the southern as barrier reefs; 

 (2) by the cutting down by marine erosion of promontories and islands and 

 of coral reefs previously elevated. 



According to Verrill( 3 ) the Bermudas have undergone a re-elevation of about 



