234 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



long. P, is 5.5 mm. long with 13 segments. P 2 is 12 mm. long with 20 segments. 

 P 3 is 9 mm. long with 16 segments. P 4 resembles P 3 . The pinnules following are 

 slender and weak, 3.5 mm. long. On another arm PI is 7 mm. long with 15 segments. 

 P 2 is 9 mm. long with 15 segments. P 3 is 8 mm. long with 14 segments. P 4 is about 

 6 mm. long. P 6 is about 5 mm. long, more slender than P 4 . In this series of speci- 

 mens the enlarged lower pinnules may be more or less prismatic with the spinous 

 ends, especially at the angles, conspicuous. P a is almost invariably absent, though 

 exceptionally present. 



One of the specimens from Arnboina Bay has the cirri with 22-25 segments which 

 in the proximal half are about twice as broad as long and in the distal half are about 

 half again as broad as long. P! is 6.5 mm. long and tapers evenly and gradually 

 from the base to the tip. It is composed of 15 segments of which the third is about 

 as long as broad, the sixth is about twice as long as broad, and the six outermost are 

 about three times as long as broad. P 2 is 10 mm. long, stouter than PI and tapering 

 much more slowly. It is composed of 17 segments of which the third is about as 

 long as broad and the sixth and following are about half again as long as broad. The 

 distal segments have finely spinous distal ends, the spines being especially prominent 

 at the angles. P 3 is 7.5 mm. long, resembling P 2 but tapering somewhat more in the 

 outer half. It is composed of 16 segments. P 4 is 4.5 mm. long with 13 segments, 

 resembling P 3 but proportionately smaller. P s is 4.5 mm. long with 13 segments 

 tapering more rapidly than P 4 with more slender and more elongate segments distally, 

 and weaker. The pinnules following resemble P s . 



In the eight specimens from Amboina P a is only exceptionally present. 



The largest specimens recorded by Eeichensperger from Little Kei, with arms 

 105 mm. long, presumably are representatives of this form. 



The four specimens from the pier at Ternate have the arms 110, 90, 90, and 30 

 mm. long. In one P 2 is practically smooth. 



The two largest of the 12 specimens from Ternate in 2-4 meters have the arms 

 95 mm. long. In one specimen with the arms 85 mm. long the cirri are XV, 19; the 

 transverse ridge on the outer segments is unmodified, or is more or less notched in the 

 middle. In another specimen with the arms 85 mm. long the cirri are XIII, 17-19; 

 the transverse ridge on the outer cirrus segments is unmodified. In a specimen with 

 the arms 80 mm. long the cirri are XII, 18-19, none of the cirrus segments are quite 

 so long as broad; the transverse ridges on the distal cirrus segments are usually 2- 

 pointed; P 2 has 16-17 segments. In another specimen with the arms 80 mm. long the 

 cirri are XIII, 17-19; the transverse ridges are unmodified; P 2 is almost smooth. In 

 a third specimen with arms 80 mm. long the transverse ridges are unmodified, P 2 has 

 18-21 segments. In two other specimens with the arms 80 mm. long the transverse 

 ridges are unmodified. In one of these P 2 has 18 or 21 segments, and is developed as 

 usual. In the other P 2 is very slender with 17-20 segments of which the longest, 

 the sixth and following, are half again as long as broad with the distal edges slightly 

 produced and on the side toward the arm tips produced into a long, broad, distally 

 curved spine. 



Remarks. This form differs from typical serripinna in being somewhat larger 

 with longer arms, in lacking P a (which sometimes is absent in typical serripinna), 

 and in having the transverse ridge on the outer cirrus segments frequently, though 



