306 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



imperfect regeneration after loss, or perhaps of arrested growth. Unfortunately a 

 study of all the postradial series was not possible on account of the close apposition of 

 the arm bases. The pinnules of the middle of the arm from about the eighteenth 

 brachial onward are usually 7 mm., rarely 8 mm., long with about 15 segments of which 

 the two first are short and those following elongate. Usually when gonads are devel- 

 oped the 2-4 segments following the second are broadened. In length and in the 

 number of their component segments the pinnules of the middle of the arm exceed 

 those of the three specimens previously described. Whether or not the distal pinnules 

 increase in length cannot be determined because of the poor state of preservation. 



The ambulacral plating consists of side and covering plates. The sacculi are 

 somewhat larger than those of the specimens already described. The disk has been 

 lost. 



In the specimen from Blake station 198 the centrodorsal is rather high and hemi- 

 spherical, as in the specimen from Blake station 219. The cirri are composed of 1519 

 segments, as in the specimens first described. 



In general the division series are as in the three first specimens, and in the one 

 from Blake station 219; but on the 10 IIBr series eight are 2 and two are 4(3+4). 

 There are 20 arms. 



The first syzygy is always between branchials 3+4, the second from between 

 brachials 17 + 18 to between bracbials 23+24, usually at about the twenty-first brachial. 

 Only five arms are well enough preserved to permit the determination of the position 

 of the following syzygies. In these the interval between the second and third syzygies 

 is 9, 11, 15, 12, and 7 muscular articulations, and the distal intersyzygial interval is 

 from 5 to 12, usually 10 or 11, muscular articulations. The intervals between the 

 syzygies are therefore somewhat greater than in the three first specimens, and in that 

 from Blake station 219. 



PI is about 8-9 mm. long with 20-25 segments, of which the first 5 are as a rule 

 broad and the second-fifth are singly carinate. The pinnules following as far as P, 

 about 8 mm. long, are of approximately the same size as PI, as in the other specimens 

 of this variety. The pinnules in the middle of the arm from about the eighteenth 

 brachial onward are 6-7 mm. long with 12-15 segments of which the two first are short 

 and those following are elongate. Usually gonads are developed; in this case usually 

 only the third and fourth segments are broadened. Whether or not the distal pinnules 

 increase in length cannot be determined because of the poor state of preservation of 

 the specimen. 



The ambulacral plating consists of side and covering plates. The sacculi are rather 

 large. The disk is 8 mm. hi diameter, as deeply incised as in the case of the first three 

 specimens, and as in var. insculpta. 



The most important characters of var. tuberosa apart from the ornamentation 

 according to Hartlaub are as follows. The centrodorsal is subhemispherical or hemi- 

 spherical with the dorsal pole small and not sharply differentiated and prominent 

 interradial processes reaching to the height of the IBri, but no interradial ridges. The 

 cirri are rather stout with 20-32 segments and an opposing spine. The radials are 

 concealed. The IIBr series are predominantly 2, rarely 4(3 + 4). The arms are 17-20 

 hi number. The first syzygy is almost always between brachials 3+4, the second from 

 between brachials 9+10 to between brachials 23+24. PI is about 9 mm. long with 



