PART 5 



A MONOGRAPH OF THE EXISTING CEINOIDS 



599 



m 



FIGURE 34. Caryomttra tinuipts (A. H. Clark), paratype of Psathyrometra acula, 

 U.S.N.M., E. 3123, Caroline station 102: a, Centrodorsal; b, proximal part of PI; 

 c, Pj; d, proximal ossicles. 



squarish. The third brachials (hypozygals of the first syzygial pairs) are wedge-shaped, 

 much longer interiorly than exteriorly; the fourth brachials (epizygals of the first syzygial 

 pairs) are oblong, rather over twice as broad as long. The fifth to eleventh brachials 

 are oblong or very slightly wedge-shaped, not so long as broad, and the following become 

 more obliquely wedge-shaped and about as long as broad. The distal portion of the 

 arms is lacking. 



Syzygies occur between brachials 3+4, again about 9 + 10 and 14 + 15, and distally 

 at intervals of 2 or 3 muscular articulations. 



PI is 5 mm. long, with 20 segments, of which the first 4 or 5 are about as long as 

 broad and the following gradually become elongated with the distal ends more and more 

 prominent until distally the segments are greatly elongated and exceedingly slender 

 with much enlarged articulations. P 2 is of about the same length but stouter and 

 stLffer, with 10 segments, of which the first is about as long as broad, the second is 

 rather longer than broad, the third is 3 times as long as broad or even longer, and the 

 following become progressively more slender and more elongated; the sixth segment 

 bears a small gonad. The folio wing pinnules to about P 6 are similar, but rather shorter. 

 P 7 and the following pinnules are 6 mm. long, little, if at all, more slender than those 

 preceding, but with shorter segments, of which the first is not so long as broad, the 

 second is about as long as broad, and the remainder become progressively elongated. 

 The segments have expanded, overlapping and finely spinous distal ends contrasting 

 with the smooth ends of the segments of the preceding pinnules, and the first 2 are not 

 broadened. 



The spicules in the perisome of the pinnules are short, slender, usually straight 

 rods with unmodified ends, or occasionally with the distal end bifurcated. They are 

 approximately a quarter the length of a pinnule segment or less. 



