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



The following pinnules gradually decrease in size and their joints become more flattened, 

 the two lowest retaining a certain amount of preponderance, being often much broader 

 than their successors. Beyond the distichal axillary, however, this is almost entirely 

 lost, the pinnules tapering gradually and symmetrically from the basal joints, which are 

 not sjjecially distinguished in any way. 



The disk (so far as it is visible) is covered with numerous small plates which are not, 

 however, set perfectly close to one another. Brachial ambulacra but httle above the 

 arm-grooves, and bordered by somewhat forked plates from which the large side plates 

 (if the pinnule-ambulacra are soon developed. 



Colour in spirit, greyish-white, with a tinge of brown at the tips of the cirri, arms, 

 and pinnules. 



Locality.— Station 209, January 22, 1875 ; lat. 10" 14' N., long. 123° 54' E. ; 

 95 fathoms ; blue mud ; bottom temperature, 71° F. One specimen. 



Remarhs. — This species is readily distinguished from the three preceding ones in the 

 same group by the greater length of the internodes in the stem. Their component 

 joints (PI. LII. fig. 3) are altogether ditferent from the lobate joints of Metacrinus costatus 

 (PL XLIX. fig. 4) and of Metacrinus nodosus (PL LL fig. 10), having the same 

 pentagonal form and horizontal ridges as Metacrinus wyvlllii (PL XLVIL fig. 4). 

 The nodal and infra-nodal joints, however, are entirely difi"erent from those of this 

 type, in which the infra-nodals are distinctly incised by the cirrus-sockets, so that 

 their syzygial surface is lobate (PL XLVIL fig. 3) and not pentagonal as in Metacrinus 

 intermptus. Another character in which this species differs very markedly from the three 

 previously considered is the small size of the basal joints on the palmar and lower 

 brachial pinnules. 



The type to which on the whole Metacrinus interruptns appears to be most closely 

 alhed is the as yet undescribed specimen dredged by the "Vega" at a depth of G5 

 fathoms in the Bay of Yedo. By the kind permission of Prof S. Lovdn, who was good 

 enough to send me some fragments of its stem, and also to allow my friend Mr. W. Percy 

 Sladen to examine it on my behalf, I am able to say that it appears to be totally different 

 from Metacrinus interrujitus. The stem-joints that I have seen have a smaller diameter 

 and a greater height both relatively and absolutely than those of that species ; and they 

 are not provided with horizontal ridges, but only with faiut tubercles at the angles, and 

 still less distinct ones at the sides. In the character of the nodal joints, however, and in 

 the absence of any extension of the cirrus-socket down on to the infra-nodals, the two 

 types are very closely similar, as they are in the length of the internodes. There seem 

 to be several other points of difference between Metacrinus interrujitus and the " Vega " 

 specimen, such, for example, as the length of the primary arms and the characters of the 

 pinnules. These will doubtless be explained more fully when the "Vega" Crinoids are 

 described • and I have therefore done no more than assign to the Japanese form a place 



