64 
THE VOYAGE OF H.M.S. CHALLENGER. 
the colour, &c. Nevertheless, further examination may prove that Cucumaria capensis, 
Cucumaria discolor, and Cucumaria planci represent dilferent types of one and the same 
species. 
Cucumaria discolor, n. sp. (PI. IV. fig. 8). 
Body subcylindrical, without any marked demarcation between the dorsal and ventral 
surfaces. Tentacles retracted, ten of almost equal size. Mouth stellate. Arms without 
teeth, and the anal portion not caudiform. Ambulacral appendages only on the ambulacra, 
completely retracted, more numerous on the ventral surface. The ventral pedicels larger, 
arranged in a double row along each ambulacrum. The dorsal appendages seem to be of 
a more conical form, present, when retracted, considerably smaller openings, and may 
possibly be considered as “papillae they are evenly arranged in double rows. Integument 
thick, leathery, with the surface smooth without any visible scales. Deposits — slightly 
concave, very delicately constructed, perforated plates or cups with numerous spines or 
knobs ; crowded buttons larger than the former, with a varying number of holes and large 
knobs ; rounded, compact reticulate thick scales of varying but never of any con- 
siderable size. A complete series of transitional forms between the buttons and scales 
occurs. Colour in alcohol, light brownish-violet, with larger and smaller darkish brown 
spots. Length, 70 mm. 
Habitat. — Simons Bay ; depth, 10 to 20 fathoms ; a single specimen. 
Not having had the opportunity of examining the dorsal ambulacral appendages in an 
extended condition, I am somewhat uncertain whether they may be referred to papillae or 
pedicels. If they were to be considered as true papillae, the species might belong to the genus 
ColocJmms, which contains forms {Colocliirus spinosus and Colochirus inornatus) presenting 
an undoubted relation to it. The ventral pedicels as well as the dorsal are in communication 
with ampullae depending into the peritoneal cavity, but those of the dorsal pedicels are 
smaller. A single Polian vesicle and madreporic canal are present. The retractors are 
attached at about the middle of the body. A small muscular stomach is present. The 
genital organs are composed of two thick bundles of simple, rather long tubes. The 
respiratory-trees are of common shape. The ventral pieces of the calcareous ring are 
inconsiderably smaller than the rest, and the undulated posterior margin of the ring is 
devoid of any processes. 
The calcareous deposits closely resemble those found in the two above cited, nearly 
related species. The exterior layer of the perisome contains numerous small, slightly 
concave, very delicately constructed perforated plates or cups (PI. IV. fig. 8, a), with the 
margin uneven, and with numerous long spines or knobs on their upper and inner 
surfaces ; they measure as much as 0‘06 mm. in diameter. The buttons which lie beneath 
the former commonly grow larger, up to 0'09 mm. or more, but it is no rarity to 
find much smaller ones provided with only four holes and a smaller number of knobs 
