120 



THREE CRUISES OF THE " BLAKE. 



smooth stem, with a rounded pentagonal outline ; it is appa- 

 rently not common, having been dredged by the " Blake " only 

 at four localities. 



Rhizocrinus (Fig. 411) has a stem composed of dice-box 

 shaped joints, terminating in a spreading root or a number of 

 branching radicular cirri, not arranged in definite whorls, with 

 a high calyx. It was first named by M. Sars, who afterwards 

 described it, in 1868, as belonging to the Apiocrinidse. But 

 before the appearance of Sars's memoir, this interesting crinoid 

 had been rediscovered by Pourtales, and stated by him to belong 

 undoubtedly to the genus Bourgueticrinus of D'Orbigny, and 

 he gave it the provisional name of B. ffotessieri, thinking it 

 might prove identical with a crinoid of that name of which 

 fragments had been found in the recent limestones of Guade- 

 loupe. Pourtales was the first to make out accurately the com- 

 position of the cup, and he of course also recognized its identity 

 with the Rhizocrinus of Sars's memoir, R. lofotensis. Rhizo- 

 crinus has been dredged by the Porcupine, the Hassler, the 



oms, from disintegrated coral rock bot- 

 tom, up came six beautiful 'sea lilies.' 

 Some of them came up on the tangles, 

 some on the dredge. They were as brit- 

 tle as glass. The heads soon curled over, 

 and showed a decided disposition to drop 

 off. At a haul made soon after we got 

 more, and, being afraid to put so many of 

 them in the tank together, I tried to 

 delude the animals into the idea that 

 they were in their native temperatures 

 by putting them into ice - water. This 

 worked well, although some of them be- 

 came exasperated and shed some of their 

 arms. They lived in the ice-water for 

 two hours, until I transferred them to 

 the tank. They moved their arms one 

 at a time. Some of the lilies were white, 

 some purple, some yellow ; the last was 

 the color of the smaller and more deli- 

 cate ones." 



I have nothing to add to the general 

 description of their movements given by 

 Sigsbee, with the exception of their use 

 of the cirri placed along the stem. These 

 they move more rapidly than the arms, 



and use them as hooks to catch hold of 

 neighboring objects ; and, on account of 

 their sharp extremities, the cirri are well 

 adapted to retain their hold. The stem 

 itself passes slowly from a rigid vertical 

 attitude to a curved or even drooping po- 

 sition. We did not bring up a single 

 specimen that showed the mode of attach- 

 ment of the stem. Several naturalists, 

 on the evidence of large slabs contain- 

 ing fossil Pentacrini, where no basal at- 

 tachment could be seen, have come to 

 the conclusion that Pentacrini might 

 be free, attaching themselves tempora- 

 rily by the cirri of the stem, much as 

 Comatulse do. I am informed, however, 

 by Captain E. Cole, of the telegraph 

 steamer " Investigator," that he has fre- 

 quently brought up the West Indian tel- 

 egraph cable with Pentacrini attached, 

 and that they are fixed, the basal extrem- 

 ity of the stem spreading slightly, some- 

 what after the manner of Holopus, so 

 that it requires considerable strength to 

 detach them. 



