504 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



specimen of conjungens stands in this respect would be of interest to learn. That 

 Antedon aeguipinna has 43 arms instead of about or exactly 40 is of no importance, 

 as IVBr series are occasionally present in one specimen from Amboina, which has 

 42 arms. 



In the larger of the two type specimens, which I examined at Hamburg in 1910, 

 the centrodorsal is broad, thin discoidal, with the cirrus sockets arranged in two 

 irregular rows; the bare dorsal pole is 4.5 mm. in diameter. The cirri are about 

 XXXVII, 22-28 (usually nearer the latter), 20 to 23 mm. long. The 40 arms are 

 about 100 mm. long. P 2 is about 17 mm. long, moderately slender, with about 30 

 segments. It is greatly enlarged on the outermost sides of the postradial series and 

 nearly as much so on the side of the IIBr series adjacent to the midradial line. The 

 segments in the outer half of the cirri have a low sharp narrow median carination. 

 The smaller specimen had probably between 25 and 30 arms. P 2 is slightly more 

 slender than usual, resembling that in the other individual. The cirri have 22-23 

 segments. 



Carpenter described Antedon imparipinna from a specimen without locality in 

 the Hamburg Museum as follows: The centrodorsal is a convex disk with a slightly 

 hollowed dorsal pole and two or three rows of cirri on its sloping sides. The cirri are 

 XXXV, 25-28. The segments are smooth and thick, becoming about square on the 

 sixth and then longer than broad, becoming shorter again toward the end. The 

 penultimate segment bears a very faint blunt spine. The radials are partially visible 

 at some of the angles of the calyx. The IBrj are widely hexagonal and are partly 

 united laterally. The IBr 2 (axillaries) are not half again as long as the IBr^ they are 

 pentagonal with wide distal angles. The lines of junction of the axillaries with the 

 ossicles above and below them are narrower than the ossicles themselves, giving the 

 sides of the postradial series a somewhat jagged appearance. The postradial series 

 divide three times, all the division series being 2. The ossicles immediately following 

 each axillary are almost completely united laterally. The 38 arms are about 75 mm. 

 long. The first brachials are almost rhomboidal, relatively long and narrow, closely 

 united to their fellows. The second brachials are shorter and more wedge-shaped, 

 longer on the outer than on the inner side. The first syzygial pair, composed of 

 brachials 3+4, is oblong. The next four brachials are nearly so, but shorter. The 

 following ones are longer, though still short, smooth, and sharply wedge-shaped, con- 

 siderably broader than long. About the middle of the arm they become blunter, with 

 forward projections alternately on opposite sides, and are squarer toward the ends. 

 The first syzygy is between brachials 3+4, the second from between brachials 13 + 14 

 to between brachials 15 + 16, and the distal intersyzygial interval is 9 to 11 muscular 

 articulations. PI is moderately long and tapers away rapidly after the basal seg- 

 ments, which are relatively rather large. P a is considerably smaller. P 2 is unusually 

 large and massive, reaching 15 mm. in length and consisting of 30 stout segments. 

 The next two pinnules (P b and P 3 ) are smaller again and about equal to Pj. The pin- 

 nules of the following pair (P c and P 4 ) are still smaller, after which the length grad- 

 ually increases, though it never much exceeds that of PI. The disk is invisible. The 

 diameter across the circle of IIBr axillaries is 13 mm. Sacculi are rather scanty on 

 the pinnule ambulacra. The color is brownish white, with traces of darker spots. 





