642 THE VOYAGE OF H.M.S. CHALLENGER. 
crowded pedicellarie. ‘The length of the longest is about 2 mm., and their delicacy is so 
great that when denuded of the membranous sheath, they are almost invisible to the naked 
eye. The actinal spines do not perhaps generally stand perpendicularly, but are directed 
laterally at a small angle to the horizontal, the plane of the direction of these spines almost 
coinciding with that of the lateral spines, with which.at first sight they might almost be 
ranked. No inner spinelet of any kind is present on the furrow-margin of the plate. 
The actinostome occupies nearly the whole of the actinal surface of the disk, its diameter 
being 4°5 mm., that of the disk being 6 mm. The buccal membrane is of great delicacy, and 
perfectly transparent, the folds of the digestive cavity being clearly visible through it. 
The mouth-plates are small and rather elongate, extending from the margin of the actino- 
stome to the interbrachial arc, the united pair having a subhexagonal outline. The 
actinostomial margin of the plates is comparatively broad and straight, with the faintest 
prominence at the median line of juncture. ach plate bears one or sometimes two small 
short mouth-spines, 0°36 mm. in length, on the adoral margin away from the median line, 
directed horizontally over the actinostome, but at an angle to the median interradial line ; 
when two mouth-spines are present the outer one is at angle of about 45°, and the inner 
one less than this. These mouth-spines can also be directed perpendicularly. Both are 
covered with thin opaque membrane, but bear no pedicellariz. On the actinal surface of 
each plate, midway between the extremities, is a comparatively large secondary or super- 
ficial mouth-spine, 1°7 mm. in length, encased in a delicate semitransparent membranous 
sheath crowded with pedicellarise. The sheath appears to terminate abruptly at a little 
distance from the tip of the spine; moreover, the pedicellariz seem to be most numerous 
on the trumpet-shaped edge of the roll, and none are present on the basal part of the 
sheath ; indeed, I am inclined to think that this disposition of the pedicellarize upon the 
sheaths obtained throughout the ray. The secondary mouth-spines are twice as thick and 
robust as any of the other spinelets on the ray. 
The plate which I regard as the madreporiform body has a very peculiar appearance, it 
is placed quite at the margin of the abactinal surface of the disk, is subtubercular, and with 
somewhat of a conchoidal form, having a single suture or “striation” furrow, resembling 
the lip of certain volute shells, passing across it. The naked portion of the plate bears 
three or four short spinelets and a few pedicellariz, the same as the other dermal struc- 
tures of the disk, above noted. The whole structure (if this indeed be the madrepori- 
form body) looks more like two displaced impinging plates than anything else. A distinct 
anal aperture is present and its position is slightly excentric. 
Colour in alcohol, greyish white, with a faint pinkish shade over the ovarial regions. 
Locality.—Station 289. In the Mid-South Pacific, near the meridian of 130° W. 
October 23, 1875. Lat. 39° 41/ 0” 8, long, 131° 23’ 0” W. Depth 2550 fathoms. 
Red clay. Bottom temperature 34°-8 Fahr. ; surface temperature 54°°5 Fahr. 
Remarks.—Freyella benthophila is characterised by the presence of six rays, a number 
