PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 789 



Syzygies occur between brachials 5+6 (on one arm 4 + 5), 9 + 10 (on one arm 8 + 9 

 and on another 7+8), and distally at intervals of usually 3, sometimes, especially in the 

 earlier portion of the arm, 2, more rarely 4 muscular articulations. 



The pinnule on the second brachial, PI, is absent. 



P 2 is 11 mm. long, slender and flagellate, tapering gradually from the base to the 

 tip, and is composed of 35 to 40 segments, of which the first two are short and the 

 remainder are about as long as broad with the corners cut away. The fourth to eighth 

 or ninth segments bear a small rounded gonad. 



The following pinnules are stouter basally and the segments beyond the gonad 

 become more and more elongated. Though large on the lower pinnules the gonads 

 come to occupy less and less space as the pinnules gradually increase in length. 



P IO is 22 mm. long, with 40 to 50 segments, of which the first two are short and very 

 slightly broader than the others, the third is about as long as broad, and the remainder 

 become progressively elongated; after the third to seventh segments, which bear the 

 small gonad, the pinnule gradually becomes exceedingly slender and distally is hairlike 

 with greatly elongated segments which have expanded, and somewhat overlapping 

 distal ends. 



After P 6 or Pj the pinnule segments develop prominent projecting and spinous 

 distal ends. 



Notes. Dr. P. H. Carpenter wrote that when he was at the Berlin Museum, Doctor 

 Hilgendorf showed him some specimens of a species of Pentametrocrinus which he had 

 collected in Japan. Carpenter believed that these were probably identical with his 

 P. japonicus, but noted that they had fewer cirrus segments, and the articulations of the 

 first 8 brachials were distinctly tubercular, the tubercle between the first two being in 

 the middorsal line, and those between the following lying alternately on either side of the 

 arm. The 3 Challenger specimens described by him as japonicus showed no traces of 

 these tubercles with the exception of the median one, which was far less marked than in 

 Hilgendorf 's specimens. 



Thanks to the kindness of Drs. W. Weltncr and R. Hartmeyer I was able, while in 

 Berlin in 1910, to reexamine these two specimens. One of these resembles the type 

 specimen from Albatross station 3661; the other is smaller, with the articular tubercles 

 less developed. With these specimens are a number of detached cirri. The largest, 

 presumably from the larger individual, are from 18 to 22 mm. in length and are com- 

 posed of 16 to 17 segments. 



At the entrance to Tokyo Bay in 600 meters Dr. Franz Dofiein dredged a fine speci- 

 men of this species, with arms about 180 mm. long and cirri 20 mm. long, with 15 to 16 

 segments. The distal pinnules are extremely slender, 23 mm. long with 35 segments. 

 The gonads are enlarged. This example is about the size of the smallest of the 3 from 

 Albatross station 3661. 



Localities. Albatross station 3661; Gulf of Tokyo, off Uki Shima; 309 meters; 

 temperature 8.89 C.; mud and pebbles; October 13, 1896 [A. H. Clark, 1907, 1908, 1921] 

 (3, U.S.N.M., 22604, 36202). Type locality. 



Japan; Hilgendorf [P. H. Carpenter, 1882, 1888; A. H. Clark, 1912] (2, Berl. M., 

 2831). 



Entrance to Tokyo Bay; 600 meters; Dr. Franz Doflein, October 27, 1904 (1, 

 ?Munich Mus.). 



Geographical range. Only known from Tokyo Bay, Japan. 



Bathymetrical range. From 309 to 600 meters. 



