REPORT ON THE HOLOTHURIOIDEA. 79 



Scotland, in the summer of 1880, Mr Murray brought home a rich collection of very 

 interesting abyssal forms, among which I was much surprised to find a great abund- 

 ance of Lcetmogone violacea. More than a hundred specimens were obtained at Station 4, 

 August 10, at a depth of 555 fathoms. 



This species differs externally from the preceding one by the considerably smaller 

 dimensions of its body and by the greater number of its dorsal processes, which 

 in general do not attain a great length. As the Holothurids dredged by Mr Murray 

 during the cruise of the " Knight Errant " have been placed at my disposal, I have had 

 an opportunity of noticing that the number of processes and pedicels even in these 

 specimens is rather variable, though it seems generally to approach that stated in the 

 diagnosis. The discoidal ends of the tentacles, about 4 '5 mm. in diameter, present in 

 resemblance to those of the preceding species no other traces of processes than a few 

 minute protuberances round their edges. The pedicels are very large, and measure at 

 their base about 8 # 5 mm. in diameter. The dorsal processes, on the contrary, are very 

 slender and of an elongated conical shape, measuring at the base about 3 mm. in diameter; 

 they vary greatly in size, and sometimes attain a length of 30 mm. or more. Like the 

 pedicels, they are highly flexible, but want the power of retraction ; however, they 

 are able to be more or less contracted. The processes are arranged in a single row 

 along each ambulacrum except anteriorly, where the two or three first of each side 

 frequently — though not always — are disposed in a transverse row, the two next following 

 being also placed side by side. The animals are in such a state of contraction that I 

 am somewhat uncertain as to the arrangement of those anterior processes. The 

 perisoma is thinner and more transparent than in Lcetmogone ivyville-thomsoni, and is 

 not so abundantly pigmented. The spicida (PI. XXXVI. fig. 24), which apparently only 

 exist on the ventral surface, are scattered, simple, spinose, and reach a length of about 

 - 16 mm. The wheels are found of all dimensions everywhere in the integument, and 

 resemble perfectly those of the above-mentioned species ; the smaller ones have as many 

 as thirteen spokes and a diameter of about 0*036 mm. ; the larger ones (PI. XXXVI. fig. 

 20), on the contrary, attain to about - 2 mm. in diameter, and possess usually eight to 

 nine spokes ; the spokes being strongly arcuated, the nave does not Lie on the same plane as 

 the felly but inside it. From the edge of the considerable hole in the centre of the nave, 

 proceed commonly four minute rods running together to a point. The wheels have the 

 appearance of a crown with the concave side turned outwards. The largest wheels are 

 found in the parietes of the processes and in the dorsal perisoma, though they are more 

 thinly scattered in the latter. The cruciform spinose bodies (PI. XXXVI. fig. 21) in 

 their most developed state reach about 0'2 mm. in diameter, while the smallest ones 

 measure only about 0*072 mm., and they are very numerous on the dorsal surface, 

 whereas they are found more scattered and commonly smaller on the ventral one ; the 

 arms of those deposits are more or less strongly arcuated and extremely spinose, 



