194 HABITS OF SOME AUSTEALIAK ECHIXI, 



Jackson it is veiy common ; Mr. Eamsay dredged up specimens 

 01 all ages and sizes from off the sandy bottom. It is equally 

 common in Moreton Bay, and a good number of specimens have 

 been brought down from Port Darwin in Nortli Australia. I 

 cannot notice any difference between the specimens brought from 

 these widely separated localities. Like all the species of Echini 

 it is gregarious, and the ''flocks" are confined to localities which 

 are often far apart. In a former paper I have given the reasons 

 which induce me to separate P. duhia from P. ^arvkj^ina nobis, a 

 species distinguished especially by its more numerous and 

 comparatively smaller spines. 



Goniocidaris is a form which has two representatives in Australia 

 Yet very little of its habits is known. The common species is 

 G. tubaria, Lamarck. It is occasionally washed up on the beach 

 after storms, and is often covered with ^r?/020«. It would appear 

 as if it loved sandy situations, and from the fact the specimens 

 come ashore singly we may suppose that it is not gregarious. 



Biadema setosum, Gray, is a species that has a very wide range. 

 It is very common on many of the Pacific Islands and in the 

 Indian Archipelago. I have seen specimens from Java. It is 

 common all along the Barrier Eeef and on the islands within it. 

 I have always found it in rocky pools at the side of the pillars of 

 dead coral which go by the name of '' Nigger Heads." Its 

 delicate spines are so long, slender, and brittle, that I should 

 imagine it must always keep on soft sandy places. But it may 

 be found sometimes adhering by its suckers to the rock under a 

 ledo-e where there is a wide sweep for its beautiful spines. When 

 in this position it is nearly impossible to obtain the specimen 

 uninjured. The spines break at the least touch, and if the hand 

 is brought incautiously near they penetrate it in aU directions, 

 breaking and leaving the fragments in the flesh. Fortunately 

 the serrated edges are turned towards the point of the spine, so 

 that the splinters work themselves out of the skin quite easily. 

 In this genus the anal system is closed by a thin naked membrane 



