Boone, Echmodermata, Cruises of "Ara" and "Alva" 123 



emphasize the rarity of Amphimetra ensifer. The geographic dis- 

 tribution of the species is substantially extended to the northeast 

 and the bathymetric range of 33 fathoms is established, placing 

 ensifer' among the deeper water species of the genus Amphimetra, 

 which have a known distribution from littoral down to 32 — possi- 

 bly 36 fathoms. 



The three specimens are, respectively, the young shown in the 

 upper figure of plate 40, and one (lower figure of the preceding 

 plate) which approximates the dimensions of the type, and a third 

 specimen, not quite so large (plate 41). All three of these speci- 

 mens have the respective centrodorsals discoidal, thick, as figured 

 by Mr. Clark for his type; the cirrus sockets are close together, 

 in two irregular, semialternate series. The cirri are 18 to 20 per 

 sea-lily, 20 to 21 millimeters long each, consisting of thirty articles 

 each, except those broken or undergoing regeneration. These 

 joints have the proportions described in the type and are similarly 

 tuberculate in the dorsal line from the tenth to distal articles, 

 except on three cirri, where the tubercles begin, respectively, on 

 the sixth, eighth and ninth articles. These dorsal spines or tuber- 

 cles are uniformly strong, conical, the proximal ten to twelve 

 being moderately developed, the distal ten being distinctly higher, 

 except when the distal one is yet longer, about subequal; the 

 opposed terminal claw strong, about as long as the diameter of 

 the preceding segment, basally thick and decidedly curved, but 

 nearly straight distally and acuminate. 



The disk has a mosaic pavement consisting of small plates. 



The arms, ten in number, are about eighty to eighty-five milli- 

 meters long (unbroken in the largest specimen). None is entire 

 in the second specimen, but the three arms, almost complete, have 

 an average length of sixty millimeters each. The cirri, twenty in 

 number, are each 18 to 20 millimeters long. This specimen also 

 has ten arms. 



The third specimen, juvenile, has ten arms, of an average 

 length of 30 millimeters (with tips broken off), and has fifteen 

 cirri, of twenty to twenty-six articles apiece, the longer cirri being 

 about 11 millimeters long, the tubercle spines beginning from the 

 eighth joint distad, these spines being relatively longer and more 

 acuminate in the young crinoid; the subdistal spine in each in- 

 stance being 1.5 to twice as high as those preceding, and the distal 

 claw of this young specimen, while possessing the characteristic 



