324 THE VOYAGE OF H.M.S. CHALLENGER. 
Pentacrinus decorus and Pentacrinus miilleri in the Caribbean Sea. There are nearly 
always five or six internodal joints in the stem, and I have only noticed two cases of an 
arm-division consisting of more than two joints united by syzygy. One has three joints, of 
which the first two form a syzygy, and in the other there are four, those of each pair being 
united by syzygy. In the arms, however, the position of the syzygies, after that at the 
base, is exceedingly variable. But this is always the case in the few species of Penta- 
erimus which have syzygies in the arms, the contrast between them and the Comatule 
being very striking in this respect. 
Pentacrinus alternicirrus appears to inhabit moderately deep water, the depths at the 
two Stations from which it is recorded being respectively 500 and 600 fathoms; while 
at the doubtful Station 210 the depth was 375 fathoms. Five of the individuals dredged 
at Station 214 (Meangis Islands) were infested with encysted Myzostomas, as were also 
many of the Comatulz. In one specimen no less than eight arms bore more or less 
perfect cysts of Myzostoma pentacrini, von Graff, two of them having two cysts a short 
distance apart. In other cases the cysts were principally formed in the skeleton of the 
pinnules by Myzostoma deformator, von Graff, as shown in Pl. XXVII. figs. 7 and 8; 
while figs. 9 and 10 represent cysts formed in the substance of the arm. 
6. Pentacrinus naresianus, n. sp. (Pl. XXVII. figs. 11-13; Pls. XXVIIL—-XXX.). 
Dimensions. 
Total length of largest specimen, stem broken at thirtieth node, - - 54:00 cm. 
Length of this stem, : : : F j : SoS 00a, 
Diameter of stem, . . ; ; : : ; 5:00 mm. 
Longest cirrus (thirty-five Rote) ‘ : 2 Z : » 20,0075 
Diameter of calyx, . : : ; : é ; fs ome 
Length of arm (eighty joints), : : 3 ; 4 f LDO00se 
Length of first pinnule (twelve joints), : : : : 8:50 ,, 
Length of pinnule from middle of arm (twenty-two soite). ; : 5 AO 
Stem long and ‘smooth, of a rounded pentagonal or circular form. Light to eighteen 
(usually about ten or twelve) internodal joints with but slightly crenulated edges. 
Nodal joints high, not projecting outwards at the angles, but deeply hollowed by the 
cirrus-sockets, which have nearly circular facets and terminate far below the upper edges 
of the nodal joints. Infra-nodals deeply grooved to receive the cirrus-bases, so that 
the sockets appear to have pyriform downward extensions. Cirri moderately slender, 
of thirty to thirty-five tolerably uniform joints, all but the lowest of which have one 
or two blunt projections on the dorsal edge. Lowest limit of the interarticular pores 
between the fifth and eighth nodes. 
Basals small, triangular or pentagonal, sometimes meeting laterally and sometimes 
1 Zool. Chall, Exp., part xxvii. pp. 62-66, 1884. 
