REPORT ON THE SPECIMENS OF THE GENUS MILLEPORA 

 COLLECTED BY DR WILLEY. 



By SYDNEY J. HICKSON, M.A.. DSc, F.R.S. 

 Beyer Professor of Zoology in the Owens College, Manchester. 



With Plates XII— XV I 



-<• 



The collection of specimens of Millepora brought home by Dr Willey consisted 

 of a few very fine dried specimens, numerous fragments and a number of pieces 

 preserved in spirit. It is of interest as exhibiting another example of the great 

 variation in the form of growth which is a characteristic feature of the genus. 



A careful examination of all the dried specimens tailed to disclose any ampullae. 

 and in none of the samples of the preserved specimens which I have examined ran 

 any trace be found of sexual organs. Many of the specimens arc very considerably 

 affected by parasites of various kinds, the details of which an- given below. 



Some of the specimens are modified in form by being simply thin encrusting 

 plates which have grown over dead corals. In a recently published paper ( 1898) I 

 have pointed out the evidence that there is for believing that at present only 

 one species of the genus Millepora is known. The evidence was obtained from the 

 study of Millepores brought from many different reefs in widely separated parts of 

 the world, and, as Dr Willev's collection assisted me materially in the investigation 

 which led to the publication of that paper, it is hardly necessary to repeat that in my 

 opinion all the specimens in his collection belong to the one species M. alcicornis Linn. 



Some of the specimens however require special description, and the question arises 

 in what manner such specimens can be named without breaking up the genus into 

 artificial groups and calling such groups " species," a plan which in my opinion is 

 misleading, or on the other hand calling the old species " varieties " and thus 

 introducing a trinomial system. 



What the author wishes to convey in a word to the reader is the general form 

 of the corallum which he is about to describe so that a mental picture may be 

 formed of the manner of growth of the coral the details of which will be learnt in 

 the text. To those who have studied the genus at all the old specific names as a 

 general rule convey to their minds this feature and this feature only, and it is 

 consequently of value to retain some or all of these names as the one-word description 

 of the form of growth. Instead of repeating therefore at the beginning of the 

 description of each specimen the words " Millepora alcicornis of the form of growth 



w. 17 



