810 SYDNEY J. HICKSON. 



On the other hand Mr Gardiner writes to me as follows : " The point you have raised 

 re Melitodes has interested me very much as it was one frequently discussed by my companion 

 and myself I held the opinion that they were all one species, and that it was only 

 a question of looking to find two or more varieties in one colony, while Cooper held 

 a contrary opinion. I then tried to find a mixture but without avail. This led me to look 

 into the matter more closely, and then I noticed that they grew in patches, generally one 

 form under each stone, though three or more forms were often in close proximity. I examined 

 them to see if some were not more in the shade or subject to different conditions than 

 others, but this was not so. I was surprised at this and therefore came to the conclusion 

 that they were distinct species." 



This valuable evidence from field notes is not conclusive, but it is of sufficient weight 

 to shake one's confidence in the contrary conclusion arrived at from work in the laboratory. 

 Further investigations are now needed on the reefs, and to assist these I will add in 

 a tabulated form my notes on the specimens, passing in succession from the North to the 

 South of the Maldive archipelago. 



A study of this table shows that the variation in the specimens throughout the Archi- 

 pelago is considerable and that with the present supply they cannot be grouped very 

 satisfactorily into discontinuous groups, varieties or facies. Moreover we have evidence (vide 

 Mr Gardiner's letter) that " three or four forms were often in close proximity," and from 

 the table that the same or very similar forms may be found in very distant localities. 

 As examples of this latter statement I would point out that the form with red nodes and 

 red internodes occurs at Miladumadulu in the extreme north of the Archipelago and at Addu 

 in the extreme South, and that the form mth yellow nodes and yellow internodes occurs as 

 far apart as Mahlos and Addu. 



The spicules of all the forms I have examined are of three kinds: (1) bent spindles with 

 the tubercles longer on the convex side than on the concave side, (2) plano-convex spicules 

 with tubercles longer on the convex side, (8) short smooth rods. The first kind occur in the 

 coenenchym of the internodes, the second kind in the nodes, and the third kind in the 

 anthocodiae. In addition to these a few smaller straight spindles, clubs or other forms of 

 spicules, occur in the internodes (fig. 11). 



The spicules of the third kind are, in all the specimens I have examined, of very nearly 

 the same size (007 mm. in length). Those of the second kind too are uniformly 013 x 0'07 mm. 

 in size. The first kind however is very variable. In the Red- Yellow variety from Hulule, 

 Male, they vary from Ol? — 025 mm. in length ; in the Red-Red variety from 014 — 0-27 mm., 

 and in the Red-Grey variety from 015 — 0-25 mm. The averages were found to be approximately; 

 Red- Yellow with a diameter of the intemode 1 mm., average length of the bent spindles 0'214 mm. ; 

 the Red-Red variety with an average diameter of the internodes 2 mm., bent spindles 0-228 mm. ; 

 and the small Red-Grey variety with an average diameter of the internode 0'75 ram.: the 

 bent spindles averaged 0-205 mm. in length. 



Taking all these points into consideration I think the best course will be to regard all 

 the specimens from the Maldives as belonging to one variable species, which for the present 

 may be regarded as new. Several species of the genus have been described by Studer (21), 

 Wright and Studer (26), and one by Ridley (19). Of these the species that seem to approach 

 it most closely are Melitodes laevis (W. and S. from Amboina) which has a similar mode of 



