A MONOGRAPH OF THE EXISTING CRINOIDS 119 



Description. — The type specimen of Antedon perspinosa from the island of Jobie 

 was thus described by Carpenter: 



The centrodorsal is discoidal. 



The cirri are about XX, about 60, long and slender. The lowest segments are 

 slightly longer than broad. Each segment in the lower and middle parts of the cirri 

 expands toward its distal end so as to overlap the base of the next segment, and its 

 edges are fringed with small spines. This overlap gradually disappears on the ventral 

 side of the later segments, and becomes gradually replaced on the dorsal side by 

 two small spines near the middle of each segment. In the terminal segments these 

 spines become smaller and closer together, and the penultimate one bears a single 

 larger spine in opposition to the terminal claw. 



The radials are partially visible. The IBri are twice as long as the radials, nearly 

 oblong, and quite free laterally. The IBr2 (axillaries) are pentagonal with a wide 

 distal angle, and are nearly twice the length of the IBri. The middle hne of the 

 articulation between the IBri and IBr2 is marked by a shght spiny tubercle, and there 

 is a similar but less marked tubercle on the articulation between the first two brachials. 

 The 10 arms are about 150 mm. long and are composed of 150+ brachials. The 

 first brachials are rhomboidal, and are almost completely united laterally. The second 

 brachials are longer and more wedge-shaped. These two brachials, and the axillaries, 

 have irregular blunt processes on their outer edges. The next four or five brachials 

 are transversely oblong. The following ones are longer, sharply wedge-shaped, and 

 overlapping. Toward the ends of the arms they become blunter and squarer. 

 The raised distal edges of all the brachials are fringed with short spines. 



The first syzygy is between brachials 3+4 and the next is usually between 

 brachials 8+9 or 9 + 10; after this the intersyzygial interval may be from 4 to 19 

 muscular articulations, being usually 4 or 5 in the lower parts of the arms and 7 or 8 

 in their outer portions. 



The lower piimules are stiff and styliform, consisting of about 15 long cylindrical 

 and overlapping segments mth expanded and spiny distal edges. Pj is shghtly longer 

 than Pi, and those following gradually diminish in stoutness and stiffness, but increase 

 in length and in the number of segments. Those on the outer parts of the arms reach 

 nearly 20 mm. in length and consist of about 30 elongated segments with expanded 

 distal ends bearing niunerous spines the outermost of which are much longer than 

 the rest. 



The disk is 7 mm. in diameter, naked and much incised. Sacculi aremoderately 

 closely set along the pinnule ambulacra. 



The color in alcohol is dark reddish brown. 



Hartlaub in 1891 noted that P. is absent in this specimen as was kindly deter- 

 mined for him at his request by Dr. R. Horst of the Leyden Museum. 



I examined this specimen at the Leyden Museum in 1910. The cirri are XIII, 

 53, 55, 56, 57, 58, and 59, long and comparatively slender, tapering slightly in the 

 distal half. The longer proximal segments are slightly (about one-third) longer than 

 broad. ?» is absent. The IBri are short, three times as broad as long. The IBra 

 (axiUaries) are also short, twice as broad as long. The synarthrial tubercles are 

 small, but well marked, with the proximal half (on the IBrO more or less spinous. 

 Pi is slightly stiffened, about two-thirds as long as Pj, and is composed of about 15 



