CENTROSTEPHANUS ASTERISCUS. 121 



The slender tridentate pedicellariae (PI. 51, fig. d) are common all over 

 the test. The valves range from .80-2.20 mm. in length and the stalk is 

 usually longer, sometimes two or three times as long. The blade is very nar- 

 row, straiglit, and somewhat compressed, and the margin is coarsely dentate. 

 The stoid tridentate pedicellarite (PI. 51, fig. A) are rare and occur on the 

 abactinal half of the test only. The valves are only .60-70 mm. in length, 

 while the stalk may be two or three times as long. The blades are broad, 

 rather flat, and considerably expanded at the tip, the only point where they 

 are in contact. The margin is irregularly serrate. Although these pedicel- 

 larire are so obviously different from the normal slender tridentate, 

 intermediate forms with the valves only slightly curved are occasionally to 

 be found. 



The glandless ophicephaloits pedicellariae (PI. 51, fig. 5) are not uncommon, 

 and are scattered all over the test. The valves are large, wide, and rounded 

 at the tip and may be as much as .60 mm. long. The stalk is several times 

 that length and appears to be entirely without glands. 



The glandular ophkephalous pedicellariaB (PI. 51, fig. 6) are common all 

 over the test and especially on the buccal plates. They do not differ essen- 

 tially from the glandless ones, but the valves are usually smaller and nar- 

 rower near the tip, and the stalk carries three large and conspicuous glands. 

 The triphyllous pedicellariae (PI. 51, fig. 7) are rather rare, but occur 

 scattered on the test. They are very small, the heads only about .20 mm. 

 long, the neck a little longer, and the stalk five or six times as long. 

 The valves are rather narrow, the blade little wider than the basal part, 

 but widest above the middle. 



The calcareous particles in the pedicels (Plate 51, fig. 11) are rather com- 

 mon. They show their triradiate origin plainly, and rarely form perforated 

 plates. 



The sphseridia are minute, scarcely .25 mm. long, and are elongated 

 ellipsoidal in form, the length nearly equalling twice the width. They are 

 pendent at the outer, lower side of the large ambulacral tubercles and 

 are not placed in depressions. Only a few (4-8) are present in each 

 ambulacrum. 



Station 4034. Penguin Bank, S. coast of Oahu, Hawaiian Islands. 

 14-28 fathoms. Fne. co. s. for. 



Station 4066. Off Ka Lae-o Ka Ilio Point, Maui, H. I. Bott. temp. 

 52.5°. 49-176 fathoms. Rky. 



