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



and styliform, consisting of about twenty smooth, flattened joints with sharp dorsal 

 edges. The disk is completely covered with a pavement of small plates, as is the brachial 

 perisome above the muscular bundles. Arm-groove moderately wide, and bordered by a, 

 discontinuous series of ambulacral plates. The pinnule-aml^ulacra have covering plates, 

 and sometimes moderately distinct side plates. 



Colour in spirit, yellowish- white, sometimes retaining a rosy tinge. 



Localities. — Station 171, July 15, 1874 ; near the Kermadec Islands; lat. 28° 33' S., 

 long. 177° 50' W. ; GOO fathoms; hard ground; bottom temperature, 39°'5 F. One 

 specimen. 



Station 214, February 10, 1875; off the Meangis Islands ; lat. 4° 33' N., long. 127° G' E. ; 

 500 fathoms ; blue mud ; bottom temperature, 41°"8 F, Several specimens. 



Uncertain — Station 210, January 25, 1875 ; off the Panglao and Siquijor Islands; lat. 

 9° 2G' N., long. 123° 45' E. ; 375 fathoms ; blue mud ; bottom temperature, 54°! F. 



Some of the fifteen specimens sent to me were without labels ; and I strongly suspect 

 that this species, together with Pentacrinits naresianus, three examples of which are 

 without labels, are those referred to by Sir Wyville, who recorded in his journal that 

 four specimens of two species of Pentacrinidse were dredged at Station 210; for the 

 collection contains no specimens at all with the label of this Station. 



Remarhs. — Pentacrimis alternicirrus, like Pentacrinus wyville-thomsoni, apjaears to 

 be pre-eminently one of those which lives in a semi-free condition, the stem having been 

 broken at a nodal joint, the syzygial face of which becomes worn and more or less rounded, 

 and has its central canal closed up. The following list shows the position of this terminal 

 nodal joint and the coi'respouding length of the stem in twelve specimens. 



Stem, 47 mm. long and terminating at tlie 11th node. 



„ 49 „ „ 11th 



„ 63 „ „ 11th 



„ C4 „ „ 11th 



„ 65 „ „ 11th 



„ 55 „ „ 12th 



„ 66 „ „ 12th 



„ 69 „ „ 12th 



„ 70 „ „ 12th 



„ 65 „ „ 14Lh 



„ 91 „ „ 14th 



„ 113 „ „ 16th 



The remarkable arrangement of the cirri in this species distinguishes it at once from 

 all the other recent Pentacrinidte. Except that the symmetry is pentamerous instead of 

 tetramerous, the arrangement recalls that of the leaves on the stem of a Labiate plant. 

 In one case only have I found any irregularity. The eighth whorl has its two regular 

 cirri like the sixth, together with an additional one which therefore comes to be on the 



