376 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



and the former states that they are longer and more delicate than 

 Lyman's figure shows ('82, pi. 4, fig. 17). I believe that Lyman's 

 figure may perfectly well be correct, for I find a similar form of the 

 radial papillae in one of the Albatross specimens that from station 

 5647 of which I show the dorsal surface on plate 85 as figure 7. 

 These papillae are here extremely small and short and a little less 

 conical than in Lyman's figure. But the other specimens for ex- 

 ample that from station 5651, of which a photograph is reproduced 

 in figure 6 have very long, fine, and pointed radial papillae. These 

 therefore show rather extensive variation. 



I give here some photographs of O. flagellata which will serve as a 

 basis for comparison with the following species, which is rather 

 closely related to it, though I have thought it best, however, to keep 

 the two separate. On these photographs the differences in form 

 shown by the upper and under arm plates on the normal arms and 

 on the parts of the arms in process of regeneration (p. 86, figs. 1, 2, 

 4, 10) may also be seen. The under arm plates are relatively narrower 

 and longer in the regenerated portions and they thus recall the form 

 observed in the young; the differences, however, are not as marked 

 as those shown in H. L. Clark's figure ('11, fig. 15Z>). 



In all my specimens the mouth shields are very large, rather pen- 

 tagonal in form, with the lateral borders more or less strongly ex- 

 cavated by the bottom of the genital slits ; they are as long as broad, 

 or even a little longer than broad; Liitken and Mortensen, as well 

 as H. L. Clark, have also shown the mouth shields as longer than 

 broad. On the figures published by Lyman, first in 1878 and later 

 in 1882, there is a lack of agreement in the form of these shields ; in 

 the figure in his bulletin (78, p. 2, fig. 49) the shield is longer than 

 broad, while in that in the Challenger report ('82. pi. 4, fig. 16) the 

 shield is very much shorter, and it may be even a little broader than 

 long. The pentagonal form with strongly excavated sides and a 

 rather narrow distal border shown by the specimen represented on 

 plate 86 as figure 2 is not peculiar to the Albatross specimens, for 

 I also find it in those which were collected by the Siboga, by the 

 Travailleur and the TalismaM,, and by the Investigator. I show the 

 ventral surface of one of these last on plate 86 as figure 1. 



I stated in 1907 ('07, p. 262) that 0. flagellata has a rather wide 

 geographical distribution; in 1899, in mentioning that the Chal- 

 lenger had found the species between the Philippines and the Caro- 

 lines, I made a slight error, to wliich H. L. Clark called attention 

 in 1911 ('11, p. 62) ; this error arose from the fact that in giving the 

 latitude of Challenger station 232 I wrote 15 instead of 35, which 

 made me say that O. flagellata had been found "between the Philip- 

 pines and the Carolines " instead of " in Japan." Since then, how- 



