200 CARNEGIE INSTITUTION OF WASHINGTON. 



treated in this manner the regeneration was equal from both halves of the 

 disk. As in the experiments with sea-water to which had been added 15 parts 

 of O.Qm. J\IgS04, regeneration was markedly slower than from the active side 

 of a specimen with one-half its sense-organs. 



In both the magnesium-treated specimens and those in which one half was 

 in contraction by means of a trapped wave, the absence of the tropic influence 

 of the sense-organs allowed the rate of regeneration to fall to that usually shown 

 by the inactive side of a specimen, one half of which retained its sense-organs. 



Report on Work at the Torres Strait Laboratory, by Hubert Lyman Clark. 



When the invitation was given me to become a member of the Torres 

 Strait expedition, I accepted with the hope that it might be possible to follow 

 out two lines of research : one was a study of the habits and reactions of living 

 crinoids under natural conditions, while the other was a general survey of the 

 echinoderm fauna of the Torres Strait region. Conditions at Thursday Island 

 proving unfavorable, it was most fortunate that Dr. Mayer decided to go at 

 once to the Murray Islands, since they proved to be an ideal situation for the 

 work. On the way thither, a 3-days stay at Erub (Darnley Island) gave a 

 glimpse of the fauna there, which, while similar to that at Maer Island, shows 

 some characteristic features of its own. On our return to Thursday Island, 

 an opportunity to visit Badu (Mulgrave Island), 25 miles to the north, proved 

 rewarding, several species of echinoderms not seen at Maer or Thursday 

 Islands being found there. 



Crinoids were so abundant at Maer Island and so easily obtained that it 

 was possible to observe their habits under normal conditions as well as under 

 the artificial conditions of the laboratory. It was found that differences of 

 habit between different genera were most marked; representatives of some 

 genera are very active, while others are very sluggish. Some move chiefly 

 by swimming, while others can hardly be induced to swim under any condi- 

 tions. There are also, as might be expected, great individual differences in 

 both normal and artificially induced movements. It was interesting to find 

 that, in spite of their fragile appearance and delicate structure, most species 

 are quite hardy and for some time endure marked changes in environment 

 and almost any amount of handling by the investigator. As crinoids are not 

 available for observational or experimental work anywhere on the coasts of 

 America or in the West Indian region (occurring there only in deep water), 

 this opportunity to study them in their natural home was most welcome. A 

 report on the results of the investigation is now in press. 



The purpose of studying the composition of the echinoderm fauna of Torres 

 Strait is to throw light not merely on the origin of the marine fauna of Australia, 

 but more especially on the origin of the littoral fauna of the South Pacific 

 islands. It is quite likely that accurate knowledge of the origin and history 

 of the echinoderm fauna of the South Pacific islands would give us new and 

 important light on the history of the Pacific Ocean and its islands. There 

 are three entrances by which the fauna of the Pacific may have come from 

 farther west: one between Japan and the Philippine Islands, one between 

 the Philip{)ines and New Guinea, and one between New Guinea and Australia. 

 Careful and thorough study of the fauna of these three areas promises, there- 

 fore, some interesting and important results. 



The echinoderm fauna of Torres Strait has been partially made known by 

 the collections of the Challenger and of the Alert, to which the collections made 

 in the vicinity of Thursday Island, in 1899, by Dr. Richard Semon, must also 

 be added. Up to the time of our visit, 117 species of echinoderms had been 



