REPORT ON THE ASTEROIDEA. 249 
ones and the margin are precisely similar to those above described, excepting that they 
bear no large spine, their tabulum being occupied by nine or more small, equal, papilliform 
spinelets, which are well-spaced and radiate slightly apart as if the surface of the tabulum 
were slightly convex. The paxillze of the outermost two rows are rather smaller than those 
of the next two rows; and those of the outermost series which represent the aborted 
- supero-marginal plates are the smallest. The paxillee of the median radial area are rather 
smaller than those of the longitudinal series ; they are rotund, bear no central spine, but have 
six to eight papilliform spinelets on the tabulum precisely similar to those above described. 
The infero-marginal plates bear along their median line a series of four to six uniform 
spines, placed one behind the other: the inner two are very small and delicate, scarcely 
worthy of being counted with the series; but the outer four are robust, tapering, and 
pointed, and increase in size slightly as they approach the margin, although the marginal 
or lateral spine is sometimes slightly smaller than its predecessor, the longest measuring 
about 4 mm. in length. The distance between the second and third spine from the 
margin is often rather greater than that between any of the others, and the space is 
occupied by two or three short, delicate, hair-like spinelets; one or two are also usually 
present between the other large spines. The margin of the keel is fringed on each side 
with rather large ciliary spinelets. 
The adambulacral plates are broad but very short, as seen on the actinal surface, and 
are united by wide ligamentous bands. Their armature, which has the appearance of 
being borne on a narrow keel, consists of three spines, arranged one behind the other, in 
transverse series in relation to the axis of the ray. The innermost or furrow spine is the 
shortest, compressed laterally, slightly curved, slightly tapering, but more or less obtuse at 
the tip. The second spine is fully two-thirds longer, more robust, only very slightly com- 
pressed, very faintly bent near the base (indeed scarcely perceptibly), tapering, and rather 
obtusely pointed. The third spine is similar, but straight, and is usually rather more 
tapering and sometimes a shade shorter and more delicate than the second spine. External 
to this spine and close to its base is usually a three-jawed pedicellaria, wide at the base 
but with delicately tapering and pointed jaws, rather more than one-third the length of 
the spine. One or two delicate ciliary spinelets may also be present. Occasionally a 
second and similar pedicellaria stands between this and the spinelets of the infero-marginal 
plates, which is either borne on a small intermediate plate (present between the adam- 
bulacral and infero-marginal plates) or at the innermost extremity of the infero-marginal 
plate ; or its position may be occupied by a small group of ciliary spinelets. 
The mouth-plates are elongate and narrow, with a series of large actinal or superficial 
spines running parallel to the margin; which are normally much larger than the marginal 
series, and increase in size as they approach the mouth. The spines at the innermost 
extremity of the plates (two or four in number) are very long, and extend nearly to the 
centre of the actinostome. 
ZOOL. CHALL. EXP.—PART LI.—1888.) 32 
