NARRATIVE OF THE CRUISK. 311 



" Nearly all the Challenger species of Actinometra were obtained at depths of less than 

 20 fathoms ; but several of those dredged by the U.S.C.S. steamer ' Blake' were found 

 at from 100 to 300 fathoms. Below the latter depth, however, there are but few records 

 of the occurrence of any Actinometra, none being known below 533 fathoms. 



" The Cape York Comatulse of both genera are remarkable for the loose way in which 

 the disk or visceral mass is attached to the calyx, a feature which is also noticeable in the 

 common rosy Feather-star of the British seas. Several specimens of the isolated disk were 

 obtained, and Sir Wyville Thomson watched them performing slow creeping movements 

 on their own account. On the other hand, the disk-less cup w r ith the arms attached will 

 continue to swim about just as readily as an entire animal does. The discovery of one 

 of these isolated disks caused much interest some fifteen years ago, for the specimen was 

 described as a recent Cystidean. Although the Challenger dredgiugs have rendered this 

 idea no loDger tenable, there is much to be said for the view which was held by Sir 

 Wyville Thomson respecting the possible interpretation of the fossil Agelacrinitidaa as 

 the isolated disks of Palseocrinoids, and not as independent organisms to be classed with 

 the Cystidca. 



" Three new genera of Comatulse were discovered by the Challenger, in addition to 

 several new species of the three previously known, Antedon, Actinometra, and 

 Eudiocvinus. All of them present characters of considerable morphological importance. 



" One of these types, for which the name Atelecrinus 1 has been proposed, was 

 obtained at Station 122, together with Peiitacr'nms maclearanns and Rhizocrinus 

 lofotensis. It seems to retain throughout life certain characters which mark transi- 

 tional stages in the development of ordinary Comatulse, and it is thus best described 

 as a permanent larval form. Atelecrinus balanoides,t\\Q species dredged at Station 122, 

 has since been found in the Caribbean Sea, by the officers of the U.S. Coast Survey 

 and Count Pourtales obtained a fragment of another oft' Cuba in 1868, while a third 

 was met with by the Challenger in the South Pacific. 



" Another very interesting new genus, for which the name Promachocrinus 2 has been 

 proposed, was dredged at Station 147, in the Southern Ocean, from a depth of 1600 fathoms. 

 It is distinguished from all other recent Crinoids by having ten primary radials instead 

 of five only. Three species were obtained during the cruise, two of them in the 

 Southern Ocean, together with Bathycrinus and Hyocrinus, and one at 500 fathoms, 

 among the Philippine Islands (Station 214). That dredged at Station 147 {Promacho- 

 crinus abyssorurn) seems to be confined to great depths, as it was also found at 1800 

 fathoms (Station 158), and like the abyssal species of Antedon is of small size. But a 

 comparatively large species was found to be abundant in the shallow water round 

 Kerguelen. Its calyx is represented in fig. 123. In the side view (a) are shown some of 

 the ten first radials, five of which rest directly upon the centro-dorsal and correspond to 



] xTthii;, incomplete. 2 xfo^a^'fi "Challenger." 



