CHAP. II.] MADEIRA TO THE COAST OF BRAZIL. 115 



widen toward the middle of the arm. The joints are wider 

 and shorter than in any of the other forms ; and the crest along 

 the distal edge, which is very distinct in P. asteria, P. Mullen^ 

 and P. Wyville-Thomsoni, is scarcely perceptible. The arms 

 consist of abont seventy joints, and there are no true syzygies 

 distal to the last radial axillaries. The pinnnles are compara- 

 tively broad and flat, and consist of about fifteen joints. The 

 disk can not be well seen in consequence of the attitude and 

 rigidity of the arms in our single example, but it appears to 

 resemble closely that of P. MilUeri. 



The structure of the stem is manifestly different from that 

 of all the hitherto described species. The nodal joints are 

 rather short and very much inflated, projecting interradially in 

 round bead-like knobs, and the inter-nodes consist of only two 

 very thin plate -like joints, so that the nodal joints with the 

 rings of cirri are crowded together. The cirri start abruptly 

 from a single nodal joint, as in P. asteria and in P. Wyville- 

 Thomsoni • they are robust, they consist of about twenty-five 

 joints, and in our specimen they are closely curled downward. 

 From the attitude of the cirri, and from the appearance of the 

 end of the stem, there can be no doubt that this specimen is 

 complete, that it is mature, and that it was living in an unat- 

 tached condition. Pentacrinus Maclearanus is thus very dis- 

 tinct from the three hitherto recognized species — P. astei'ia, P. 

 Mi'dleri, and P. Wyville-Thomsoni ; perhaps it approaches the 

 last most nearly, but it differs from it markedly in the structure 

 and arrangement of the arms, and totally in the construction of 

 the stem. 



