MONOGRAPH OF THE EXISTING CKINOIDS. 599 



OccuiTcnce of comatuUds in half submerged caves. — In the Tropics half sub- 

 merged caves, on account of the protection which they afford against the brilliant 

 glare of the tropical sun, often form extraordinarily rich nurseries for many types 

 of marine organisms, and comatulids have occasionally been found to be abundant 

 in such situations. 



Ahsence of comatulids fi'oin rock pools. — It might be expected that rock pools 

 would offer very favorable conditions for comatulid existence, but they are seldom 

 or never found in such situations, preferring always open water. 



Occurrence of comatulids beneath stones. — In southeastern Australia and in 

 southern Japan the local species of Compsomctra, which are very small, are fre- 

 quently found beneath stones along the low-tide mark. 



In Europe Antedon often occurs similarly, and is very prone to withdraw into 

 deep recesses, where individuals often grow to an unusually large size. 



Occurrence of comatulids on piling. — In many East Indian harbors where the 

 water is especially pure comatulids are frequently seen clinging to the piling of the 

 wharves and docks, and to the chains and under sides of buoys. 



In some places in the Mediterranean and on the Atlantic coasts of Europe 

 Antedon has been found in similar situations. 



Breakwaters. — It has long been known that the seaward side of breakwaters 

 in the Indo-Pacific region and in the Mediterranean basin is a favorite habitat for 

 comatulids, especially of the smaller species. The outer side of a breakwater is 

 quite comparable to the outer side of an exposed ledge or reef. 



Occurrence of comatulids on mangrove roots. — The only comatulid which Dr. 

 Th. Mortensen collected in the course of his investigations in Siam, Amphimetra 

 discoidea, was found clinging to mangrove roots. 



Occurrence of comatulids on mud. — Comaster novceguinece, Amphimetra dis- 

 coidea., and A. papuensis have been taken on muddy bottoms in sheltered situations, 

 a very unusual habitat for littoral crinoids. 



Possible occun^ence of a comatulid on sand. — On the sand flat on the southern 

 side of Friday Island, Torres Strait, Dr. H. L. Clark picked up a specimen of 

 Zygometra punctata. It is not quite clear from his account whether the animal 

 was actually living there, or whether it had been washed up; the latter is more 

 probable. 



Occurrence of Antedon bifida at Roscoff. — The best account of the occurrence 

 of Antedon bifida as a strictly littoral animal is that given by Prof. H. de Lacaze- 

 Duthiers outlining the status of that species at Koscoff as he knew it there. 



Describing the locality he writes that the port of Eoscoff, situated at the 

 northern extremity of a broad tongue of land which projects northward into 

 the English Channel between the rivers of Morlaix and St. Pol-de-Lpon on the 

 east and the Bay of Pouldu on the west, is protected by numberless reefs, bare 

 at low tide, on which the zoologist can collect the most varied animal types. 

 Moreover, the Gulf Stream, which bathes these coasts, gives to these regions 

 a temperature which is in a high degree suited to the development of the animals. 



To the north Bass Island, a long strip of land granitic like the other rocks, 

 runs east and west, forming a barrier against the waves of the open sea and pro- 

 142140—21— Bull. 82 40 



