288 



ANTEDON. 



Centro-dorsal a tmncated hemisphere, marked by indistinct interradial ridges, which are pro- 

 duced upwards into rather prominent processes between the radials. Twenty to twenty-five cirri, 



of eighteen to twenty-three smooth joints, most of which 

 are slightly longer than wide; the penultimate without 

 an opposing spine. 



First radials entirely concealed; the second quite 

 short, especially in the middle line, barely in contact 

 above the angles of the centro-dorsal. They are deeply 

 incised by the tubercular backward processes of the 

 axillaries, which sometimes almost reach the centro- 

 dorsal. Three distichals, the junction of the first two 

 somewhat tubercular, and the axillary a syzygy, in close 

 contact with its fellow on the next ray. The outer 

 radials and the three distichal joints have sharp straight 

 edges, and both sides flattened, and the first two or 

 three brachials may show the same characters, but to 

 a less extent. 



Fourteen to twenty arms, of over one hundred 

 joints, of which the lowest are nearly oblong, their suc- 

 cessors triangular, and wider than long, gradually be- 

 coming longer and more quadrate. 



The first syzygy is in the third brachial when the 

 primary arms do not divide, and the next between the 

 eleventh and fifteenth. When distichals are present 

 the first two bracliials are usually united by syzygy, 

 and the next syzygial joint is from the seventh to the 

 twenty-fifth brachial, usually about the twelfth or four- 

 teenth. After this an interval of four to twelve, gen- 

 erally six or seven joints, between successive syzygia. 



The distichal pinnule is about 9mm. long, and con- 

 sists of some thirty short, carinate joints, the lowest of 

 which, though thick, are not specially wide. The next 

 two or three pinnules are of about the same length, 

 with relatively longer terminal joints, and the lower 

 ones somewhat flatter. The following pinnules are a 

 little shorter, with the first two joints smaller than in 

 the proximal pinnules; but the third joint and from two 

 to four of its successors are broad and flattened, with 

 the outer edges much produced towards the ventral 

 side. Traces of this expansion may be visible as far as 

 the twenty-fifth brachial, after which the joints become 

 elongated and the pinnules more slender. 



The disk is much incised and completely plated, as 

 are also the brachial ambulacra and the interarticular 

 spaces. The genital glands are covered by closely set 

 plates in which sacculi are imbedded. These are small 

 and inconspicuous on the pinnule-ambulacra, which 

 have well-defined side plates. 



Colour in spirit, — light whitish-brown. Disk 7mm. ; 

 spread 15cm. 



Aus Griinden, welche sich aus dem Fol- 

 genden ergeben, sei bier auch die Beschrei- 

 bung, welche Carpenter von A. inaequalis 

 Carp. (Chall. Rep., 26, p. 244, pi. 2, fig. 5, 

 und pi. 51, fig. 2; p. 246, fig. 5a) gegeben hat, anschliessend angefuhrt: 



Fig. 2. A. inaequalis Carp. (Nach Car- 

 penter, Chall. Rep., pi. 51, fig. 2). 



