REPORT ON THE ASTEROIDEA. 145 



the end of the ray the papillae are turned back and directed slightly over the furrow, 

 instead of being closed down upon the surface of the plate, and the pit is probably aborted. 



The mouth-plates form a rather broad mouth-angle, presenting a well-developed keel 

 along the median line of junction, more or less imperfectly closed along the suture and 

 widely open at the aboral extremity. A single, short, conical, sharply pointed mouth- 

 spine to each mouth-angle stands at the innermost point, and in the median line. Two 

 large segmental papilla) occupy nearly the whole of the lateral portion of each mouth- 

 plate ; they stand close together, touching one another, and the aboral one is the larger 

 of the two. (See PL XXVII. fig. 6.) 



The actinal interradial areas are small, and the squamous intermediate plates are 

 comparatively few in number, these being rather large in the immediate angle, though 

 very narrow and elongate near the margin. 



Colour in alcohol, greyish white, excepting the abactinal membrane, which is 

 bluish grey. 



Locality. — Station 298. Off the western coast of South America, between Valparaiso 

 and the Island of Juan Fernandez. November 17, 1875. Lat. 34° 7' 0" S., long. 73° 

 56' 0" "W. Depth 2225 fathoms. Blue mud. Bottom temperature 35°'6 Fahr. ; surface 

 temperature 59° - Fahr. 



Remarks. — This species is distinguished from Porcellanaster crassus, the only other 

 form having segmental pits and papillae, by its short and delicate rays, by its com- 

 paratively unarmed supero-marginal plates, and by the limitation of the spinelets 

 on the abactinal surface to definite areas. 



6. Porcellanaster eremicus, 1 n. sp. 



Since my preliminary notices on the species of Porcellanaster " were written I have 

 received a very young form which had been found in a bottle of other material that 

 had been sent to America. It is without doubt a Porcellanaster, and at a very early stage 

 of growth. The measurements are B = 6'5 mm.; r = 3 - 25 mm. The form appears 

 to be nearly related to Porcellanaster cseruleus, and the most striking, if not the only 

 real specific difference that I can detect at this stage is that the rays are longer, more 

 attenuate, and thinner throughout. 



At such an obviously early phase it would serve no good end to endeavour to draw 

 up a specific diagnosis which would enable the adult stages to be recognised when found. 

 I shall therefore limit myself to some remarks on the interesting features presented 

 by this example. As I feel convinced, however, from the characters shown by the young 

 form, and from the isolation of the habitat, that the species is distinct, I have ventured 

 to assign a name to it. This course will also facilitate reference. 



1 lerifiixbs, accustomed to solitude. 



2 Joum. Linn. Soc. Lond. (Zool.), 1883, voL xvii. p. 214. 



(ZOOL. CHALL. EXP. — PART LI. — 1887.) 19 



