724 



680— " THETIS " SCIENTIFIC RESULTS. 



And from Turtle Bay, Dirk Hartog Island : — 



Capillaster muUiradiata 



Decametra studeri 



Ptilonietra macronema. 

 In short it may be said that from the point of view of the 

 Crinoids the coasts of Australia form an integral part of the 

 great Indo-Pacific- Japanese faunal region. With its area of 

 maximum intensity lying within a triangle whose apices are 

 roughly Luzon, Borneo, and New Guinea, this faunal region 

 extends southward, embracing the northern coasts of Australia, 

 and down either side of that Continent, becoming progressively 

 more and more attenuated as one proceeds southward, reaching 

 Shark Bay on the west and Sydney on the east coast. At these 

 points it undergoes a transformation, and a fauna is evolved 

 which, while strictly East Indian, is at the same time character- 

 istically Australian, so that the southern coasts of Australia 

 north to Shark Bay and Sydney may be said to constitute a 

 South Australian subregion, characterized by one peculiar genus 

 (closely related, however, to two East Indian genera) and seven 

 peculiar species distributed among five genera, the one just 

 mentioned (Ptilometra) and four others, all of which extend 

 not jhward to China or Japan. 



I have said that the fauna of the Australian coasts north of 

 Sydney and Shark Bay belongs to the Indo-Pacific-Japanese 

 region ; that is, it is made up entirely of Indo-Pacific-Japanese 

 genera and species. It has, however, a curious entity of its 

 own, a composition which at once distinguishes it from the fauna 

 of any other district, and renders it possible to recognize a 

 collection of Crinoids from any part of the region at once as being 

 Australian. 



Among the Comastericlse there are four species peculiar to 

 North Australia; these are: — 



Coniatula rotalaria 



Comatula etheridgei 



Comatula purpurea 



Comanthina belli 

 And, strangely enough, they all represent extreme types. 



The genus Zygometra includes in this region three peculiar 

 species : — 



Zygometra microdiscus 



Zygometra muUiradiata 



Zygometra elegans 

 And, most singularly, these are the three most specialized species, 

 with the larjfest number of arms in the genus. 



