REPORT ON THE HOLOTHURIOIDEA . 73 



and brittle in consequence of a great number of crowded spinose perforated plates 

 overlapping one another (PI. XXXV. fig. 9); these plates reach the enormous size of 

 0"88 mm. or more. The five longitudinal muscular bands, as well as the digestive tract 

 and the pseudhaemal vessels, contain a number of deposits in the form of spicula or of 

 perforated irregular plates (PI. XXXV. figs. 7, 8, and 10). 



Lcetmogone, The'el. 



Lcetmofjone, Thdel, Preliminary Report on the Holothuriilne, pp. 9-10. 



Tentacles fifteen, rather large, not retractile. The lateral ambulacra of the ventral 

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

 face. The odd ambulacrum naked. The dorsal surface with extremely elongated, flexible, 

 cylindrical, non-retractile processes, disposed in a single row all along each of its ambul- 

 acra. Integument with numerous wheels, and beside* those deposits spicula or cruciform 

 bodies. 



Lcetmogone wyville-thomsoni, The'el (PI. XL and PI. XII.). 



Lcttmogune wyville-thomsoni, Thdel, Preliminary Report on the Holotlnimla?, p. 10. 



Body very elongated, cylindrical or fusiform, several times longer than broad. 

 Mouth anterior, subventral. Anus posterior, terminal, slightly dorsal. Tentacles of 

 almost equal size ; their terminal part large, thick, and sole-like, destitute of visible 

 processes. Pedicels varying greatly in number from about fifty-six in all — twenty-nine 

 along the left side and twenty-seven along the right — to only fifteen along each side of 

 the ventral surface or less. Processes of each of the dorsal ambulacra rather slender, 

 very flexible, and varying from sixteen or seventeen to about five ; their length varying 

 greatly, some being very short, others as long as the length of the body ; a rather short 

 genital process placed in the medio-dorsal line, a little behind the tentacles. Integument 

 very thin and soft, with three kinds of calcareous deposits : scattered spicula, very large, 

 frequently rather straight and unbranched ; large wheels with about ten spokes ; and 

 smaller wheels with ten to thirteen spokes, both sorts of wheels concave, the felly being 

 directed outwards, not on the same plane as the nave ; the wheels have somewhat the 

 form of a crown. Between the large and small wheels there are many forms, varying 

 much in size and shape. 



Colour in alcohol, lighter and darker violet, often inclining to dirty brown ; ends of 

 the tentacles leather-coloured. Length of the largest specimen, 240 mm. Breadth, 

 about 50 or 60 mm. 



Habitat. —Station 147. December 30, 1873. Lat. 46 c 16' S., long. 48° 27' E. 

 Depth, 1600 fathoms ; bottom temperature, 0'8° C. ; globigerina ooze. Three specimens. 

 Station 158. March 7, 1874. Lat. 50° 1' S., long. 123° 4' E. Depth, 1800 fathoms; 



(ZOOL. CHALL. EXP.— PART XIII. 1881.) N 10 



