1900.] MARINE FAUNA OF CHRISTMAS ISLAND. 121 



long), from what I take to have been a prostrate, or other one-sided 

 growth-form. The branchlets are all turned up one side and 

 grow out at right angles, and the scoop-shaped radial calicles 

 project on the same side also at right angles and are chiefly 

 obsolete on the opposite side. The branches show no trace of 

 fusing together. In other respects, however, it comes nearest to 

 Madrepora dathrata. The calicles, both radial and axial, seem to 

 agree in shape and size, and the characters of the coenenchyma 

 seem to be the same as those described for this species. 



The specimens of this and the next species were broken from 

 dense clumps growing on the reef-flat in water about one foot 

 deep at low tide, when the tops of the clumps are exposed for 

 some time. 



Madrepora valida. 



Madrepora valida Dana, Zoophytes, p. 461, pi. 35. fig. 1. 



There is a complete specimen consisting of a crowd of processes 

 all reaching to about the same height (4 cm.), and rising from a 

 common incr listing base, which seems to come near Dana's type. 

 The tips of most of the processes in the single specimen had been 

 injured, and the coral had attempted to heal the injuries. The 

 axial calicles and a few of the nearer radial calicles are swollen 

 into ccenenchymal knobs, without or with greatly reduced or 

 distorted calicle apertures. Where not injured, the calicles have 

 much the aspect described and figured by Dana, and the section 

 of the processes shows the density of the coral, also mentioned by 

 Dana. 



Madrepora (?) aspera Dana. 



Madrepora aspera Dana, Zoophytes, p. 4GS, pi. 38. fig. 1. 



A specimen 8 cm. high, in which the tapering branches more 

 or less suddenly proliferate into a number of stunted outgrowths. 

 The septa in the radial calicles show it to belong to the subgenus 

 Eumadrepora Brook. The size of its axial corallite, the variously 

 prominent and labellate radial calicles interspersed with minute 

 obsolete calicles, seem to ally it with M. aspera. It differs chiefly 

 in the greater crowding of the radial calicles, which were com- 

 paratively sparse in the type specimen. 



This species forms dense clumps growing on the reef-flat, and 

 partly exposed at low-water. 



Madrepora delicatula Brook. 



Madrepora delicatula Brook, Ann. & Mag. Nat. Hist. viii. 1891, 

 p. 461. 



There are two small detached clusters of twigs which agree 

 with the branchlets of Brook's type of M. delicatula. The measure- 

 ments and shapes of the calicles both axial and radial agree, as 

 also do the markings on the surface as described. 



There is no evidence that the growth-form resembled that of 



