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



and their slightly enlarged ends are directed outwards from the body, thus making 

 the integument very rough. Here and there such bodies composed of three or five arms 

 are to be distinguished. There is no difference in the individuals brought home by the 

 "Knight Errant" with regard to the size and number of the cruciform bodies of the 

 dorsal and ventral surfaces, but it is worthy of note that those deposits are more 

 irregular and differ more frequently from the typical four-armed form, a greater number 

 of them being formed by three, five, or six arms than is the case in the examples dredged 

 at Station 164. In the pedicels, processes, and tentacles a smaller or greater number of 

 wheels and X-shaped bodies are distinguishable. The ends of the pedicels are provided 

 with a perforated terminal plate — sometimes only fragments of the plate are visible — 

 which gives the impression of being hollowed and concave outwards with its edge thick 

 and of a more irregular net-like structure ; round this plate a number of straight or 

 slightly curved unbranched spicula is crowded, most of which are rather large and thick 

 and towards the spinose ends either acute or obtuse (PL XXXVI. fig. 22). The walls of 

 the dorsal processes contain scattered spicula, and the terminal discoidal part of the ten- 

 tacles is strengthened by a great number of extremely arcuated ones (PL XXXVI. fig. 23). 



The water- vascular system resembles that of the preceding species ; however, 

 the ambulacral cavities of the pedicels are in this form narrower and more elongated 

 (PL XLII. fig. 2). The madreporic canal is supported by calcareous deposits of irregular 

 shape, which constitute a particularly strong network where the tube cbngs to the body- 

 wall. The madreporic tube terminates in several minute canals, which pierce the perisoma 

 and open externally close to the base of the genital process. 



The calcareous ring forms as in Lcetmogone luyville-thomsoni a continuous whole 

 round the gullet, and does not appear to be composed of separate ossicles ; only a more 

 solid structure marks the position of the radial pieces. 



Lcetmogone spongiosa, Thdel (PL XIV.). 



Cryodora spungiosa, Theel, Preliminary Report on the Holotliuridas, p. 9. 



Body elongated, almost cylindrical, and of equal breadth throughout, about four times 

 as long as broad. Mouth anterior, subventral. Anus posterior, subdorsal. Tentacles of 

 almost equal size, their terminal part large and discoidal, destitute of visible processes. 

 Pedicels fourteen along the left side of the ventral surface, and fifteen along the right, 

 the posterior ones xexy small and indistinct. Processes of the dorsal surface eighteen 

 along the right and seventeen along the left ambulacrum, rather long, very soft and 

 flexible ; the four anterior on each side not in a row after one another, but two and two, 

 side by side. Integument very thick, soft and spongy with three sorts of calcareous 

 deposits : wheels, spicula, and four- or five-armed spinous, starlike or cruciform bodies. 



Colour in alcohol, light sea-green ; top of the tentacles light brown. Length, 

 135 mm. Breadth, 35 mm. 



