REPORT ON THE CRINOIDEA. 231 



pair are of the same character, but less stout, though not much shorter. The following 

 pinnules become more slender and gradually increase in length. 



Disk naked and moderately incised ; the ambulacra have lines of sacculi at their sides, 

 which become very prominent towards the margin of the disk, and give off branches to 

 the first pair of pinnules. The sacculi are large and abundant along the ambulacra of 

 both arms and pinnules. 



Colour in spirit, — the skeleton reddish-white, with dark red lines at the articulations ; 

 perisome grey or purplish-grey. 



Disk 15 mm.; spread 20 cm. 



Locality.— Station 208, January 17, 1875; off Manila ; lat. 11° 37' N., long. 123° 

 31' E.; 18 fathoms; blue mud. One specimen. 



Remarks. — This type is readily distinguished from the only two other bidistichate 

 species of Antedon in which the rays divide but twice. It differs from Antedon disci- 

 formis (PI. XXXIX. fig. 4) in the presence of a pinnule on the third brachial, the 

 shorter arm-joints, and the smaller number of cirrus-joints (PL XL. fig. l); while the 

 second pair of pinnules are relatively much stouter than in Antedon clemens, and the 

 number of cirrus-joints is smaller than in that type (PI. XXXIX. fig. 5). In the freedom 

 of its rays and in the irregular processes at their sides it resembles Antedon tuberculata 

 (PL XLV. fig. 2), but differs from it in having a smaller number of cirri and no palmars 

 developed, so that there are only fourteen arms instead of thirty, while the lengths 

 of the first pinnules are much more nearly equal than is the case in that type (PL XLV. 

 fig. 3). 



The second pair of pinnules of this unique specimen of Antedon marginata terminate 

 so abruptly that they seem to have been broken by some accident and not completely 

 repaired. The diameter of the joints suddenly decreases and there are from one to four 

 quite small joints at the end of a large and stout one which is considerably longer than 

 wide. 



The disk of this specimen is remarkable for the abundance of sacculi upon it. 

 There is a line of them along each side of the ten secondary ambulacra ; and branches 

 proceed direct from these lines to the primary pinnules as seen in PL XL. fig. 2, 

 thus marking the course of their water-vessels, which, however, have no tentacular 

 extensions. This character recalls the arrangement of the pinnule-ambulacra on the disk 

 of Metacrinus as figured on pi. xxxix. fig. 2 and pi. xliii. fig. 3 of Part I. But in 

 Antedon marginata the lines of sacculi and the water-vessels are unaccompanied by the 

 other ambulacral structures, and the lower pinnules are non-tentaculiferous, as in Antedon 

 rosacea and other types. 



