82 THE VOYAGE OF H.M.S. CHALLENGER. 



number of the calcareous bodies, it is safest to regard these two forms as belonging to 

 different species. 



Orphnurgus, Theel. 



Orphnurgus, Thdel, Preliminary Eeport on the Holothurida?, p. 8. 



Tentacles twenty, rather large, non-retractile. The lateral ambulacra of the ventral 

 surface with very large pedicels, disposed in a single row all along each side of that 

 surface, and with another series of slender, flexible processes, placed above the pedicels, all 

 along each side of the body. The odd ambulacrum naked. The dorsal surface with a 

 crowded series of numerous processes, resembling those of the ventral lateral ambulacra, 

 apparently disposed in two rows all along each of its ambulacra. Integument with 

 spicula of various forms. 



Orphnurgus asper, Theel (PL XV.). 



Orphnurgus oyer, Th^el, Preliminary Eeport on the Holothuridfe, p. 8. 



Body very elongated, of almost equal breadth throughout, several times longer than 

 broad. Mouth anterior, terminal, slightly ventral. Anus posterior, slightly dorsal. 

 Tentacles of almost equal size ; one smaller than the others, with its terminal part torn 

 off ; ends of the tentacles with several retractile branched processes. Pedicels twenty- three 

 along each side of the ventral surface, very large and long ; the posterior ones smaller. 

 Number of processes along the lateral ambulacra of the ventral surface almost the same as 

 that of the pedicels. Processes of the dorsal ambulacra very numerous, in all about one 

 hundred and fifty. The length of the slender and flexible processes variable, the largest 

 ones nearly as long as the breadth of the body. Integument hard and rough, with 

 numerous small, short spicula of various shapes, some smooth, others provided with 

 numerous large spines or processes. 



Colour in alcohol, light grey. Length, about 170 mm. Breadth, about 35 mm. 



Habitat.— Station 23. March 1 5, 1 873. Off Sombrero Island. Depth, 450 fathoms ; 

 globigerina ooze. One specimen. 



The only specimen which I have had at my disposal was extremely incomplete and 

 much contracted and wrinkled, so that it was rather difficult to ascertain exactly 

 its true aspect, but I believe that my figures present a pretty correct idea of its 

 shape. The body is very elongated and of almost equal width throughout. The ventral 

 surface is almost flat, while the dorsal one, on the contrary, is convex. The anal aperture 

 is very large. 



On account of the contraction of the dorsal perisoma it is impossible to state exactly the 

 position of the processes in correspondence with one another as well as with the pedicels. 

 The processes, about two hundred in number, including those of the ventral lateral 

 ambulacra, are of an elongated conical form, and the largest measure about 25 to 30 mm. 



