HOLOTHDEIAKS OP NEW ZEALAND. 37 



tentacles are retracted) than the posterior. Tentacles ten, 

 tufted with short branches ; the two ventral much smaller than 

 the eight others. 



Integument hard, covered with a close armour of imbricating 

 scales. In the anterior and posterior portions of the body the 

 scales overlap very regularly, the free edges pointing towards 

 the extremity in each case. In the middle third the arrange- 

 ment is less regular. The colour of the living animal is pink, 

 and the colouring-matter appears to be located in the central 

 portion of each scale. The oral and anal openings are guarded 

 by a few irregular nodules. 



The fully developed tube-feet appear to be confined to the 

 middle third of the ventral surface of the body. They are very 

 numerous and arranged in three crowded ambulacral bands. 

 They have sucking-disks and ampullae. Small papillse are irre- 

 gularly scattered over the dorsal surface, but chiefly on the 

 ambulacral areas. Both tube-feet and papillae die away towards 

 the extremities, leaving the terminal portions of the body smooth 

 but scaly. Both are far more numerous in the larger specimens. 



The internal anatomy is typical. The five retractor muscles 

 are well developed. The alimentary canal is very long and much 

 convoluted in the middle part of its length, but still showing the 

 usual arrangement in descending and ascending loops. The 

 rectum is long, its actual dimensions varying with the state of 

 contraction of the animal. The two respiratory trees are well 

 developed and copiously branched, and extend forwards to the 

 anterior end of the body. The genital organs consist of two 

 voluminous tufts of slender caeca, situated in the middle third of 

 the body, from which the genital duct runs forward dorsally 

 along the mesentery to open close to the crown of tentacles (if 

 not actually between two of them). There is a single Polian 

 vesicle, attached to the ambulacral ring a little to the left of the 

 mid-dorsal line, and a single madreporic canal attached dorsally 

 (PI. 4, fig. 33). The calcareous ring (PI. 4. fig. 34) consists of ten 

 Y-shaped pieces with their forks directed posteriorly. (In the 

 radial pieces, to which the retractor muscles are attached, the 

 single arm of the Y appears to be jointed on to the fork, but 

 this is probably due to accidental fracture, caused by the excessive 

 contraction of the muscles.) The radials and interradials are 

 more nearly equal and similar than in C. alba. 



The principal spicules are large and small, flat, reticulate 



