REPORT ON THE ASTEROEDEA. 257 



towards the tip. is obtuse there. This spinelet is normally directed over the furrow and 

 separates the adjacent tube-feet. The other two spinelets are subequal, are a little longer 

 than the furrow spinelets, measuring at the base of the ray 4 mm., and are delicate, 

 cylindrical, and tapering, but truncate at the tip, and often with a faint tendency to 

 flare. On the aboral side of the outermost spine is one very small, short, cilia-like spinelet. 



The mouth-plates are elongate, narrow, and strongly keeled ; their armature consists 

 of a marginal series which extends the whole length of the plate, very small and papilli- 

 form along the line of union with the adambulacral plate proper, and only the inner three 

 or four on the free part of the margin larger and spiniform ; the innermost two on each 

 plate are close together, often flattened and apposed, and form what may perhaps be 

 looked upon as an incipient pedicellarian apparatus, which is directed horizontally over 

 the actinostome at an angle of 45° to the median radial line. On the actinal surface of 

 the plate is a lineal series of spinelets, robust and large along the greater part of the plate, 

 but diminishing in size as they recede from the mouth, becoming rapidly mere small 

 papillae at the outer end of the plate. 



In the very limited actinal interradial area there are generally two or three additional 

 pedicellarise exactly similar to those on the small intermediate plate which separates the 

 iufero-marginal and adambulacral plates along the ray. 



The madreporiform body is situated very near the margin, and is usually hidden by 

 paxillae ; its appearance is more or less spongiform rather than " madreporiform ; " and 

 the striations are coarse, with definite foramina distinctly visible here and there. 



Colour in alcohol, a warm shade of brown over the paxillar area, becoming nearly brick 

 red at the extremity of the ray ; the terminal or ocular plate white. The centre of the 

 disk and a narrow well-defined band traversing the median abactinal line of the ray are 

 marked with a much darker colour, approaching dark purple, which gives a very striking 

 appearance. Actinal surface a bleached yellowish white. 



Localities. — Simon's Bay, Cape of Good Hope. 



" Porcupine " Expedition : 



Station 36. 1870. In the Strait of Gibraltar, off the coast of Morocco. Lat. 35° 35' 

 N., long. 6° 2(3' W. Depth 12S fathoms. Bottom temperature 12° 9 C. ; surface 

 temperature 2 3° '8 C. 



Remarks. — This species is nearly allied to Luidia sarsii of the North Atlantic, of 

 which it is unquestionably the representative. Both are five-rayed forms, but Luidia 

 qfricana is of much larger size, and the rays taper gradually from the base to the tip, 

 living them a very pointed and attenuate appearance. The paxillse on the median portion 

 of the rays are very much smaller than in Luidia sarsii, and the central granule is less 

 prominent than in that form throughout. In Luidia africana the uppermost or lateral 

 spine on the infero- marginal plates is the largest, whereas in the northern species this is 

 generally smaller. In like manner, the outermost of the three spines on the adambulacral 



(ZOOL. CHALL. EXP. — PART LI. — 1888.) 33 



