30 



BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



O.lmm 



VOLUME 1 



a 



FIGURE 2. Aporometra wilsoni (Bell), syntype, B.M., 93.7.8.8: a, Diagonal view of centrodorsal 

 and proximal part of postradial series; b, peripheral cirrus; c, PI; d, Pj; e, spicules from pinnule 

 ambulacra. 



and the one preceding being much roughened dorsally. Some of the ambulacral spicules 

 are illustrated in figure 2. 



The species is viviparous as H. L. Clark found to be the case in A. occidentalis. 

 The more advanced embryos have reached the stage shown by Mortensen in Isometra 

 mvipara, illustrated in his work of 1920 (pi. 22, figs. 6-8) on crinoid development. 

 No ciliary bands can be seen. 



Notes. A specimen from Port Phillip in the Australian Museum has the 10 arms 

 25 mm. long. The cirri, which are XI, two to each radial area excepting in one case 

 where there are three, are from 28 to 33 mm. long. 



The elements of the IBr series resemble those of Ptttometra macronema. They 

 and the first two brachials have the lateral edges perfectly straight and somewhat 

 produced into a narrow flange-like border by which they are in lateral apposition. A 

 broad synarthrial tubercle is just beginning to develop. 



The arms are rounded dorsally with no trace of carination. The pinnules are 

 rounded and not prismatic, though the larger show traces of a prismatic condition in 

 the basal segments. The marginal lappets of the pinnule ambulacra are calcified. 



