MONOGRAPH OF THE EXISTING CEINOIDS. 601 



fond of living. Among these rootlets also ascidians, sponges, sertularians, and 

 bryozoans are so numerous that each root yields quite a collection in itself. 

 Antedon is sometimes present in such quantities that, by wrapping its arms about 

 them it almost by itself alone gives color to the stems, and as it occurs in all 

 possible sizes this seems to be a situation especially suited to its development. 



With this thought in mind, Professor de Lacaze-Duthiers undertook a search 

 for the pentacrinoids, and his anticipations were immediately realized; even on 

 the beach itself he was able to collect very fine specimens. But he found it more 

 convenient to carry away the roots covered with Antedons and to search through 

 them in the laboratory with a magnifier under water. In this way he found penta- 

 crinoids of all ages. He kept them alive for some time, and was able to observe 

 their metamorphosis. They cast off the column characteristic of the crinoidal 

 form, became free, and mingled with the adult and adolescent Antedons, from 

 among which it became impossible to distinguish them. 



In order to verify the observations of Sir Wyville Thomson and Dr. W. B. 

 Carpenter, MM. Lemire and Myevre, after having worked a long time in the labo- 

 ratories of Professor de Lacaze-Duthiers under his direction, both at the Museum 

 of Natural History and at the Sorbonne, on his advice went to Roscoff. 



M. Lemire did not leave Roscoff until after the spring tide at the beginning 

 of October, and at that time he was no longer able to find pentacrinoids; already 

 in September their number had appeared to be perceptibly reduced, although a 

 great many Antedons could still be found. M. E. Grube, of Breslau, who had come 

 at the instigation of Professor de Lacaze-Duthiers at the commencement of Sep- 

 tember and whom he had the pleasure of conducting along the shores not only 

 of Roscoff but also of St. Pol-de-Leon, to which place they made numerous 

 excursions together, was able to confirm this. 



Therefore it appears that the pentacrinoids can be found with certainty only 

 in the summer months. 



About Roscoff pentacrinoids are very restricted in their occurrence. Prof, 

 de Lacaze-Duthiers in his excursions in the neighborhood of Roscoff, for example 

 to Kainou, a plateau of rocks situated southeast of Sainte Barbe in the river of 

 St. Pol-de-Leon, which is not uncovered except at the lowest tides, to the north 

 of Thizaouson, to the west of the fort of Perharidi and of the Roche du Loup, 

 never found them, although seaweed abounds at almost all these localities. The 

 conditions peculiar to the streamlets sheltered behind Green Island are there- 

 fore without doubt the most favorable for the spawning of Antedon and for the 

 development of the young. 



Prof. Charles Gravier tells me that the relative abundance of Antedon bifida 

 on the French coasts is subject to great variations; in some years they are very 

 common, while in others they become rare. 



Prof. F. J. Bell in his account of the comatulids of the Maldive and Laccadive 

 Islands states that they seem especially to frequent the inner ends of the passages 

 where they embouch into the lagoons. 



