THE 
VOYAGE OF H.M.S. CHALLENGER 
ZO OLOGY. 
REPORT on the Holotiiurtoidea dredged by H.M.S. Challenger during 
In this second part of my work on the Holothupjoidea I have not limited my labours 
to a description of those forms of the Apoda and Pedata which were brought home by 
the Challenger Expedition, but have added a short exposition of all shallow-water forms 
hitherto known. It was considered that such a monograph was highly desirable. It 
should not be forgotten, however, that the difficulties of a monograph are very great, 
especially in the case of the Holothurioidea, and that larger and smaller gaps must 
necessarily occur because of the frequent imperfection in the desciiptions of many 
authors. Besides the Challenger collections, I have had at my disposition for comparison 
the very rich collection of the State Zoological Museum in Stockholm, kindly placed in 
my hands by Professor S. Loven, a prett}’' large collection of tropical forms belonging to 
the GodelFroy Museum, and divers forms, partly types, from the Mediterranean and 
Mauritius, for the use of which I feel extremely obliged to Dr. E. von Marenzeller and 
Professor Karl Mobius. 
The examination of the vast harvest brought home by the Challenger Expedition 
from different regions of the world, from the shore as well as from the abysses of the 
ocean, shows clearly that those Holothurids which live in the deep sea have two different 
derivations. The great majority are Elasipoda, which cannot be derived from the 
present shallow-water fauna, but must have originated from a past type that certainly 
bore another stamp. On the other hand, so far as can be judged from the results of the 
INTRODUCTION. 
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