122 REPORT ON THE SPECIMENS OF THE GENUS MILLEPORA 



attributed to Millepora species by authors," I propose to abbreviate it in each case 

 thus, ' Millepora alcicornis Facies ' x,' " or simply " Facies x," where " Millepora 

 alcicornis " is understood. 



The word " Facies " as it will be used will not convey more than the word 

 " Colour " does in the description of species. 



When we speak of a horse of black colour no one assumes that we mean a 

 horse belonging to a black coloured species, and similarly when I use the expression 

 "a Coral of dichotomous facies" or of "facies dickotoma" I do not mean more than 

 that the particular specimen described happens to be of this form of growth. 



MILLEPORA ALCICORNIS. 

 Facies dichctoma. 



There are several pieces of corallum which under the old system would have 

 been included in the species Millepora dichotoma (Forskal). 



Forskal's original definition of this species is as follows, " retiformis, laeviuscula, 

 ramis teretibus, subcompressis, apice obtusissimis, poris minutis," and he adds in the 

 more detailed description that the colour is " flavicans " and the habitat " profundum." 



Forskal's specimens, like those described later by Klunzinger, came from the 

 Red Sea. 



The specimen collected by Dr Willey, from which the photograph (Fig. 1) was 

 taken, is 15 centimetres in height and spreads out in one plane to a width of about 

 18 centimetres. The branches are slightly compressed and in the centre of the 

 mesh reach a thickness of about 7 mm. 



The degree of fusion in the branches is very variable. In one place, seen to 

 the left of the centre in the figure, the branches have fused to form a plate 

 3 centimetres in breadth. In other specimens plates larger than this may be seen. 



The surface of the corallum is generally smooth, but near the base of the " live ' " 

 corallum several irregular protuberances may be seen. These protuberances are due 

 to the irritation caused by the growth of parasitic Algae 2 and worms. 



These Algae are very common on the specimens, attacking not only the basal 

 parts but in some cases the growing points. In one fragment a distinct spherical 

 gall has been formed which can only be attributed to the effort made by the 

 Millepore to surround and overwhelm the Alga which had attacked it. Parasitic 

 cirripedes are rare on the Millepores of this facies, but as one fragment exhibits 

 the characteristic key-hole aperture of Pyrgoma inilleporae it cannot be said that 

 they are free from the attacks of cirriped parasites. 



The cycles of pores are on the whole well marked, but it will be noticed on 



1 This term is used in its conventional sense and refers only to those parts of the corallum which were 

 invested with living tissues when the specimen was killed by the collector. When a Millepore or a portion 

 of a Millepore dies in its position on the reef the surface is attacked by parasites and sedentary creatures 

 of various kinds and is thereby altered so materially that there can never be any doubt that it was dead 

 if it be subsequently examined. 



2 It is difficult to identify this Alga, but it appears to be closely related to Laurencia caespitosa Lamour. 

 vel hybrida. Annal. Bot. v. 



