302 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



like tlie paired spines in Cenoraetra, assumes a median position shortly after its appear- 

 ance; in the species of tlio genus Oligometrides (fig. 35,3, p. 293) the transverse ridge 

 moves to a position near the proximal edge of the segments, and a second transverse 

 ridge appears near the distal edge. The opposing spine of Oligometra (fig. 352, 

 p. 291) is slender, median, and perfectly erect, and the terminal claw, as usual in 

 the Ohgophreata, is rather stout and strongly curved in its pro.ximal tliird, becom- 

 ing more slender and nearly straight distaUy. The cirri in Cyllometra (figs. 346- 

 34S, p. 289) in general resemble those of Oligometra, but they may be even more 

 primitive in having some of the earlier segments slightly elongated, thougli tliis 

 is only the case in a few species; the transverse ridge may be very high, taking 

 the form of a liigh tri- or bidentate dorsal spine. The cirri of Decametra (fig. 

 349, p. 291) and Petasometra are just like those of Cyllometra. The cirri of Colobo- 

 metra (fig. 350, p. 291), wliich are much elongated, are composed of segments which 

 are sometimes longer than broad proximally, very short distally; at first there 

 is a serrate transverse ridge, formed by the recession of the everted chstal dorsal 

 ends of the segments, which soon divides in the middle and resolves itself into a 

 pair of dorsal spines; at the extreme tip these two spines fuse into one. The 

 proximal cirrals of Colohometra, like those of Zenometra (fig. 109, p. 175), have 

 the distal edges all around armed with long sharp spines, like the edges of the 

 calyx plates. 



The cirri of the species of Atelecrinidse (figs. 405, 406, p. 311, and 414, p. 319), 

 except Atelecrinv^ anomxilus, are but imperfectly known, as the perfect tip has 

 never been observed. So far as can be seen they are of the same smooth, strongly 

 compressed type as that found in all of the Pcntametrocriuidae, and in such genera 

 as Iridometra, Coccometra, Psathyrometra and T1iysanom,etra; except in Atelecrinus 

 anomalus (fig. 414, p. 319), wliich has cirri resembling those of Pentametrocrinus 

 tuberculatus, the component segments are greatly elongated, with somewhat swollen 

 distal ends, which are often more prominent along the ventral profile than along 

 the dorsal, the reverse of what is usually the case. At the present state of our 

 knowledge tliis feature is sufficient to identify the cirri of tliis family. 



In the Pentametrocrinidse (figs. 113, p. 181, 119, p. 185, 120, p. 187, 121, p. 189, 

 and 404, p. 311) the cirii are smooth, with more or less, often greatly, elongated 

 segments, wliich are strongly compressed laterally. In the species mth very long 

 cirri, like Pentametrocrinus varians (fig. 119, p. 185) or P. japonicus (fig. 404, p. 311), 

 these end in a small, short and straight conical terminal claw; but in the species 

 •with short cirri, like P. diomedese. (fig. 120, p. 187) or P. tuberculatum (fig. 121, 

 p. 189), the terminal claw is considerably longer than the penultimate segment, 

 stout basally but tapering (hstally, comparatively straight in the basal half, but in 

 the distal half strongly curv'od ilownward. 



The cirri of the species belonging to the large family Antedonidse, as would 

 be expected, exliibit a very great degree of variation, though they are all constructed 

 after tlie same general plan. They may be described as more or less compressed 

 laterally, especially in the distal portion, slender, the earher segments more or less 

 elongated and centrally constricted, the outer becoming shghtly shorter, though 

 never very short, and without true dorsal spines (except in Zenometra), though the 



