PART 6 A MONOGRAPH OF THE EXISTING CRESTOIDS 757 



Zool., vol. 19, No. 32, 1928, p. 11 (notes). FELL, New Zealand Science Congress, 1947, p. 209 

 (listed; range); Tuatara, Wellington, New Zealand, vol. 3, No. 2, 1950, p. 84 (in key), text- 

 fig. 14 (calyx and arm bases). 



Diagnostic features. The cirri are about XXX, with 12 to 16+ segments, of which 

 the longest are about four times as long as their median width, the antepenultimate is 

 about a third again as long as broad and the penultimate is hardly, if at all, longer than 

 broad; P 1 has about 20 segments, of which the first two or three are not longer than 

 broad but the following ones become very elongate with expanded and spiny joints; P 2 

 is probably shorter and may bear a gonad. When the arms are about 25 mm. long the 

 cirri are 7 to 8 mm. 



Description. The centrodorsal is broadly rounded conical, 1.2 mm. in diameter 

 and 0.8 mm. high, with the well-marked cirrus sockets irregularly placed and crowded. 



The cirri are XXV-XXX, a middle one has 16 segments and is 7 mm. long; the 

 apical ones are shorter with fewer segments and the peripheral (which are all lost) 

 were probably a little longer. The first segment is about as long as broad, the second 

 is half again as long as broad, the third to sixth are nearly or quite four times as long 

 as the median width, and the following slowly decrease in length to the penultimate 

 which is slightly or not at all longer than broad. The longer segments are centrally 

 constricted and distally flared, especially on the shorter cirri, and the distal are laterally 

 compressed. The opposing spine is well-developed, terminal, and directed obliquely 

 forward. The terminal claw is strongly curved. 



The distal edges of the radials are just visible beyond the rim of the centrodorsal. 

 The IBri are very short, about four times as broad as the lateral length, with the 

 anterior border somewhat incised. The IBr 2 (axillaries) are rhombic, broader than long, 

 with the distal edges concave. 



The 10 arms were probably not more than 25 mm. long. The first brachials are 

 twice as long exteriorly as interiorly, with the inner half of the distal border parallel 

 to the proximal border and the outer half running upward at a considerable angle, while 

 the inner borders barely meet over the sharp anterior angle of the axillaries. The 

 second brachials are much larger, and irregularly quadrate. The first syzygial pair 

 (composed of brachials 3+4) is half again as long as broad, and nearly oblong. The 

 following brachials to the second syzygy are oblong or almost square, those succeeding 

 becoming almost triangular, longer than broad, and distally more elongate with 

 gradually less and less oblique and more and more swollen ends. 



From the proximal edge of the IBr 1 to the second syzygy is 5.0 mm. and the width 

 at the first syzygy is 0.6 mm. 



Syzygies occur between brachials 3+4, 9 + 10, and 14+15, and distally at intervals 

 of 2 muscular articulations. 



P : is slender, about 7 mm. long, and consists of 20 elongated segments, of which the 

 longer outer ones are expanded and spiny at the joints. P a is similar, but shorter. 

 P 2 and P b are still shorter, but have stouter segments and one or both of them bear a 

 well-developed gonad. The following pinnules gradually increase in length, becoming 

 slender and delicate with the two basal segments more or less flattened. 



The above description is mainly of the syntype from station 169, with the exception 

 of the cirri which are only present in the specimen from station 170A. 



Localities. Challenger station 170A; near the Kermadec Islands, north of New 

 Zealand (lat. 2945' S., long. 17811' W.); 1152 meters; temperature 4.17 C.; volcanic 

 mud; July 14, 1874 [P. H. Carpenter, 1888; A. H. Clark, 1913] (1, B.M.). 



