62 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



the collecting has been undertaken — in most cases under the able leader- 

 ship of Dr. Waldo L. Schmitt, with the enthusiastic support of several 

 young collectors — the material now assembled appears to be so complete 

 that one dares assert that very few additional species are to be expected. 

 Future investigators must be content to secure more material of the 

 species now known or additional information about the distribution of 

 the individual species. 



The collections consist chiefly of material collected in less than 100 

 fathoms, or what is usually referred to as shallow water, in contrast to 

 the truly deep sea. The species are distributed among the following four 

 orders — Dendrochirota, Aspidochirota, Molpadonia, and Apoda; the 

 fifth order, Elasipoda, made up exclusively of deepwater forms and a few 

 Arctic species from shallow water, was not met with by the Velero. The 

 Dendrochirota and Aspidochirota have the greatest numbers of repre- 

 sentatives. The material of the former order has proved to be the most 

 interesting, because it includes a large number of new species which are 

 restricted to the Panamic region or have close relatives in the West Indies, 

 while the representatives of the Aspidochirota are mostly widespread 

 species. The Molpadonia and Apoda have so few representatives that it is 

 difficult to make any general statements about their relations to other 

 faunas. 



In the following account all the Dendrochirota hitherto known from 

 the Panamic region are monographically treated. Besides the material 

 secured by the Velero III, a few undescribed specimens from the M.C.Z. 

 have been included to make the work complete. Much use has also been 

 made of Selenka's old types and other material from the Panamic region 

 which I have had occasion to examine at various times. Special attention 

 has been paid to comparison with the holothurians from adjacent waters, 

 that is, the West Indian, Californian, Chilean, and Hawaiian seas. As far 

 as the Dendrochi rotes are concerned, one may say that the affinities are 

 definitely with the West Indian fauna, while a few forms have related 

 representatives in Californian waters. Several species are also known 

 from the Chilean coast, but relationship to the Hawaiian fauna seems to 

 be nil. More extensive explorations may, however, show that a somewhat 

 richer Dendrochirote fauna exists in Hawaii than has hitherto been sup- 

 posed. 



It is a great pleasure to thank the Allan Hancock Foundation for the 

 privilege of studying this valuable collection, thus enabling me to realize 

 my long-felt desire to write a monograph on the holothurians of the 



