250 THE VOYAGE OF H.M.S. CHALLENGER 



The actinal interradial areas, -which are very small and narrow, probably do not contain 

 more than a pair or so of small intermediate plates ; and the area has the appearance of 

 being covered with small ciliary spinelets. 



The madreporiform body is hidden by paxillae. 



The ambulacral tube-feet have large rounded terminal knobs. 



Colour in alcohol, a snowy white, mottled with irregular patches of intensely dark- 

 brown almost black, but lighter in some places and approaching mouse-colour. Actinal 

 surface and lateral spines white, also the central conical spine on the tabulum of the 

 paxillae, whether the paxilla itself be white or black. Ocular or terminal plate white. 

 The mottling and the sharp contrast of the patches of colour give a remarkably handsome 

 character to this starfish. 



Individual Variation. — In a ten-rayed example the paxillae in all the regular longi- 

 tudinal series at the sides of the rays may have a central conical spinelet on the tabulum, 

 but those in the outermost two rows are much less pronounced. The rays are slightly 

 shorter and the disk broader: R=166 mm., r= 22-23 mm. The colour mottling may 

 also affect the lateral spines in places. 



Young Phase. — Small immature specimens, which I refer to this species, were collected 

 at Stations 204 and 219. Each example has ten rays, and their characters accord so 

 closely with the foregoing description that I feel little doubt about placing them as the 

 young of Luidia aspera. The largest has a radial measurement of 45 mm. As might 

 naturally be expected at this early stage of growth, the central spinelet on the tabulum of 

 the paxillse near the sides of the rays is very feebly developed, and is in fact so small as 

 to almost escape notice on superficial examination. Otherwise the characters of the adult 

 are well displayed. 



Localities. — Samboangan, Philippine group. Depth 10 fathoms. 



Station 204. Off Tablas Island, Philippine group. November 2, 1874. Lat. 12° 43' 

 0"N., long. 122° 9' 0" E. Depth 100 to 115 fathoms. Green mud. Surface tempera- 

 ture 84°-0 Fahr. 



Station 219. North of Admiralty Island. March 10, 1875. Lat. 1° 54' 0" S., long. 

 146° 39' 40" E. Depth 150 fathoms. Coral mud. Surface temperature 84°-0 Fahr. 



Remarks. — This species is characterised by the form of the paxillse and by the arma- 

 ture of the infero-marginal plates. The nearest ally in its own area of distribution is 

 Luidia macidata, from which it may be distinguished by the particulars just mentioned. 



2. Luidia alternata (Say), Llitken. 



Asterias alternata, Say, 1825, Journ. Acad. Nat. Sci. Philadelphia, vol. v., pt 1, p. 144. 

 Luidia alternata, Lutken, 1860, Videnskab. Medd. naturh. Foren. i Kj0benhavn for 1859, p. 42. 



Locality. — Challenger Expedition : Bahia. Depth 7 to 20 fathoms. 

 Other Localities. — Florida, Breton Island, Tortugas, St Thomas. 



