THE ASTEROIDEA OF THE MERGUI ARCHIPELAGO. 



319 



of large size, and differs somewhat in the marginal contour from 

 Australian and New-Zealand specimens ; the odd anterior radial 

 area being rather more prominent, and the anterior pair of inter- 

 radial areas natter in their curvature, which causes the margin of 

 the test to be less fully rounded in front, and the greatest 

 breadth to be more conspicuously posterior to the postero-lateral 

 petals. The marginal contour is, however, subject to such a great 

 amount of variation throughout the family, that we do not con- 

 sider it of sufficient importance to give a name to the variety ; and 

 until a further series of examples is available, we confine ourselves 

 to the simple record of the circumstance. 



Ou the Asteroidea of the Mergui Archipelago, collected for the 

 Trustees of the Indian Museum, Calcutta, by Dr. John 

 Anderson, F.H.S., Superintendent of the Museum. By W. 

 Percy Sladen, F.G.S., Sec. L.S. 



[Read 21st June, 1888.] 

 (Plate XXVIII.) 



The collection of Asteroidea made by Dr. Anderson in the 

 Mergui Archipelago, although small, is particularly interesting. 

 It is noteworthy, not only from the fact that it contains several 

 new as well as rare forms, but also because some of the examples 

 which I have referred to known species show r variations which are 

 sufficient to impart a character to the collection as a whole, and 

 to indicate the existence of local conditions whose action upon 

 types of a more plastic nature than that of the series of forms 

 so far collected would probably result in new morphological 

 developments. That the representatives of other forms occur 

 in this area is highly probable ; and it seems to me, therefore, a 

 reasonable expectation that a number of " new species " may 

 ultimately be found in the Mergui Archipelago when further 

 dredging operations are carried out. From what I have seen, I 

 think it is not too bold to throw out the suggestion that the 

 Mergui area may be looked upon as a moulding ground wherein 

 Malayan types assume a modified form, approaching to a certain 

 extent the Indian-Ocean facies, but maintaining a local and 

 independent character. 



