THE 



VOYAGE OF H.M.S. CHALLENGEK. 



ZOOLOGY. 



REPORT on the Gephyrea collected by H.M.S. Challenger during the Years 

 1873-76. By Dr. Emil Selenka, Professor in the University of 



Erlangen. 



INTRODUCTION. 



Among the Gephyrea collected during the Challenger Expedition, many diifercnt genera 

 are represented, but the number of species is comparatively small. The twenty-eight 

 species to be afterwards discussed are distributed over eleven genera, and these 

 already known. Two of these genera were indeed described as new by the late R. 

 von Willemoes-Suhm in his letters published in the Zeitschrift fiir wissenschaftliche 

 Zoologie and in his manuscript notes. But an examination of the original specimens 

 has shown that one of these is really a Bonellia, and the other, designated Leioderma, 

 n. gen., by v. Willemoes-Suhm, a true Phymosoma. The latter species, along with some 

 other more or less damaged specimens, must, moreover, be excluded from our description, 

 since their state of preservation was not such as to admit of an accurate diagnosis of 

 their specific characters. None of them, however, exhibited any important peculiarities. 



The habitat and distribution of some of the species are of special interest. Some 

 forms which had previously been found only near the shore, were on the Challenger 

 Expedition dredged from very considerable depths. One new deep-sea species was foimd 

 in the Pacific and also in the North Atlantic Ocean, and in regard to other forms the 

 range of distribution was shown to be much wider than had hitherto been recognised. 



If one may venture to draw general conclusions from the scanty matei-ial at our 

 disposal, it appears probable that the tube-inhabiting Gephyrea (genus Phascolion and 

 many species of Phascolosoma) occur especially in the greater depths, where as yet there 

 has been found only a single example of the free-living forms of the genus Phymosoma. 



(ZOOL. CHALL. EXP. — PART XXXVI. — 1885.) Nn 1 



