496 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The two first brachials are a little longer exteriorly than interiorly. The first syzygial 

 pair (composed of brachials 3+4) is about as long as broad. The next three or four 

 brachials are discoidal, and these are succeeded by a moderately long series of short 

 brachials, which are at first more or less triangular but later become bluntly wedge- 

 shaped. Their distal border sometimes bears dorsally a small sharp process situated 

 on alternate sides. The outermost brachials are as long as broad, though remaining 

 feebly wedge-shaped. A characteristic feature of many arms is that their greatest 

 width is reached at some distance from their base. The first syzygy is between 

 brachials 3+4, the next usually from between brachials 13 + 14 to between brachials 

 17 + 18, and the distal intersyzygial interval is 8 or 9 muscular articulations. The 

 two outer arms of the four arising from each IIBr axillary have longer lower pinnules 

 than the two inner, and P 2 on the two outermost arms of each postradial series is 

 remarkable for its special stoutness. These features are as a rule very pronounced, 

 and when this is the case the disk is surrounded by 20 long pinnules, which are dis- 

 tributed in ten pairs, the two of each pair belonging to the outer arms of adjacent 

 IIIBr series. 



P! on the outer arms is thin and slender and has a very variable number of seg- 

 ments, these numbering between 12 and 35. It is about half as long as P 2 , which is 

 moderately stiff and is by far the longest and thickest pinnule of the arm. It has a 

 length of 10 to 17 mm., and the number of its uniform smooth cylindrical segments 

 may exceed 30, although very often there are not more than 14-20. The segments 

 are about as long as broad. P 3 as a rule is very small, and P 4 is the smallest of all. 

 The succeeding pinnules slowly increase in length, finally reaching about 5 or 6 mm. 

 The two first pinnules on the inner side of the outer arms (P a and P b ) are usually much 

 shorter than the corresponding pinnules of the outer side; but P c and P,, are of about 

 the same length as P 3 and P 4 . The disk is about 17 mm. in diameter and is deeply 

 incised. Sacculi are thickly set on the pinnules. In color the dorsal skeleton shows 

 different shades of brown, often variegated with a light gray-brown in bands and 

 spots; the central portion is often uniform light gray or whitish brown. The disk is 

 gray or gray-brown. Gray-blue specimens also occur. 



Prof. Ludwig Doderlein recorded two specimens from Amboina under the name of 

 Antedon imparipinna. He said that the assertion in Hartlaub's key to the species of 

 the Palmata group that in imparipinna P 2 has 25 or more segments is misleading, 

 though in the description of the species Hartlaub correctly states that the number is as 

 large as this only on the outermost arms of each postradial series, this pinnule on the 

 inner arms having not more than 14-20 segments. He said further that these elon- 

 gated pinnules are in no way styliform or stiff, their condition not being quite satis- 

 factorily expressed in Hartlaub's figures. 



The eight specimens from Amboina recorded by Dr. August Reichensperger have 

 32-40 arms 70 to 100 mm. in length In four specimens P 2 is very long and slender, 

 up to 18 mm. in length, and is composed of 28-30 segments. The cirri are XXV- 

 XXXVIII, 26-29. The arms are closely appressed laterally. Another specimen has 

 32 arms. P 2 is only 11 mm. long, with 26-28 segments, and is very slender. The 

 cirri are in this weaker and somewhat shorter than in the others and are composed of 

 about 25 segments. Three specimens have P 2 up to 16 mm. long, stouter basally than 

 in the preceding specimens and standing up more stiffly, flagellate only in the distal 



