REPORT ON THE ASTEROIDEA. 523 



The armature of the adambulacral plates consists of four (but often towards the extremity 

 only three), short, delicate, acicular, and well-spaced spines. Three stand on the 

 margin of the plate parallel to the furrow, the aboral being the smallest and the adoral 

 nearly twice as long. The fourth spine, which is equal in length to the last-named, 

 or even longer, is placed close to it, but on the outer side and away from the furrow. 

 These two spines are present throughout the ray, and maintain this position. The 

 three marginal spines are usually stretched horizontally over the furrow, but the fourth 

 spine is almost perpendicular, and frequently radiates at an angle outward (away) from 

 the furrow. The spines are covered with an investing membrane, which in the three 

 marginal spines is expanded towards the tip and gives them a claviform appearance, the 

 most adoral one of the three being more robust than the others ; in the fourth or outward 

 spine the investment is even more developed, and the covered spine presents a somewhat 

 more lanceolate shape than those just referred to. The aperture-papillae are very singular in 

 form, and consist of a comb of about five to seven radiating spinelets springing from a 

 common base, the central spinelet being straight and much longer than the others, which 

 are curved, the two outer ones forming together a regular semicircular span, and the rest 

 radiating within this curve, at gradually lessening angles of divergence from the central 

 spinelet. The investing membrane by which the papilla is covered owes its form in a great 

 measure to this skeleton. It is ovate or oblate basally, with an elongate acicular promi- 

 nence in its outward prolongation. Near the extremity of the ray this central shaft of the 

 papilla is greatly lengthened, being little shorter than the lateral spines. 



The mouth-plates are short, but extraordinarily broad, the lateral flanges being developed 

 to an abnormal extent. The keel at the junction is feebly represented, only flatly rounded, 

 slightly prominent aborally, the adoral peak being well developed. One moderately robust, 

 short, conical spinelet, very wide at the base, sharply pointed, and covered with membrane, 

 is placed near to the adoral extremity of each plate, and rather above the actual margin. 

 No other secondary or superficial spine is present. There are three mouth-spines, about 

 equal in size to the spines of the adambulacral armature, placed on the extreme outer 

 portion of the lateral flange, and sometimes the outer one is doubled. 



The actino-lateral spines are delicate and well spaced. Sixteen are present on each 

 side of a ray, the third or fourth from the mouth being usually the longest, and the rest 

 gradually diminishing in size as they approach the extremity of the ray. 



Colour in alcohol, abactinal surface white, with the faintest shade of pink ; actinal 

 surface scarlet ; ambulacral tube-feet white. 



Locality. — Station 146. Between Marion Island and the Crozet Islands. Decem- 

 ber 29, 1873. Lat. 46" 46' 0" S. ; long. 45° 31' 0" E. Depth 1375 fathoms. Globi- 

 gerina ooze. Bottom temperature 35° - 6 Fahr. ; surface temperature 43°"0 Fahr. 



Remarks. — The almost venated character of the disposition of the muscular fibres in 

 the supradorsal membrane, the peculiar character of the armature of the adambulacral 



