A MONOGRAPH OF THE EXISTING CRIXOIDS 59 



All the segments from the transition segment omviml bear prominent dorsal spines 

 which on the 3 or 4 terminal become very small. The opposing spine is low, less than 

 one-fourth the width of the penultimate segment in height, and rounded. The ter- 

 minal claw is longer than the penultimate segment, stout, and moderately curved. 



The disk is naked, except for a few scattered granules near the periphery. The 

 brachial ambulacra are naked. The pinnule ambulacra have moderately developed 

 side and covering plates. The sacculi are small. 



The ends of the basal rays are visible as irregular tubercles in the intcrradial angles 

 of the calyx. 



The radials are concealed by the centrodorsal. The IBr, are almost entirely con- 

 cealed, but their apposed sides are visible as triangles in the interradial angles. The 

 IBr 2 arc rhombic, about twice as broad as long, produced posteriorly over the IBr,, 

 with the borders slightly prominent and a moderately sharp median keel. The HIV 

 series arc 2, with the axillary rhombic and over twice as long as the preceding ossicle; 

 both are bluntly carinate in the median line, and their borders are slightly prominent. 

 The division series are sharply flattened laterally and are in close lateral apposition. 

 The first 15 brachials are also sharply flattened laterally. 



The 20 rather slender arms are 130 mm. in length. The first 2 brachials are wedge- 

 shaped, the latter larger than the former and with a rounded posterior projection. The 

 following 11 brachials are oblong or slightly wedge-shaped, about twice as broad as 

 long, those succeeding gradually becoming somewhat more obliquely wedge-shaped, 

 about as long as broad, and slowly less obliquely wedge-shaped distally, and elongate 

 terminally. After about the proximal third of the arm the brachials develop promi- 

 nently overlapping distal edges which are armed with fine spines. The arms are strongly 

 compressed laterally in the basal third, and moderately compressed distally. 



Syzygics occur between brachials 3+4, again between brachials 23 + 24 and 32 + 33 

 and distally at intervals of from 4 to 9 muscular articulations, the intersyzygiaJ interval 

 decreasing distally. 



PI is 7 mm. long, considerably stouter than P 2 though not especially enlarged, 

 tapering evenly from the base to the tip. It is composed of 15 segments all of which 

 are about as long as broad, P 2 is 5 mm. long with 13 segments of which the first is about 

 as long as broad and those following become progressively elongated, reaching a length 

 of 2 or 3 times the width distally. The following pinnules gradually decrease in length 

 to P 8 or P 7 , then become rather more slender and increase to 7 mm. distally. 



The color in alcohol is brownish yellow, the calyx and arm bases to the fourth 

 brachial dark brown, the cirri light yello \visli. 



Locality. Albatross station 3S82; Hawaiian Islands; Pailolo Channel, between 

 Maui and Molokai; Mokuhooniki Islet bearing N. 30 W., 3.1 miles distant; 249 meters; 

 sand, coral, and rock; bottom temperature 17.5 C.; April 16, 1902 [A. H. Clark, 1908, 

 1909, 1912, 1918, 1949; Gislen, 1934] 1, U.S.N.M., 22689). 



History. This species was described under the name of Thalassometra crassicirra 

 in 1908 from a single specimen from Albatross station 3SS2;at the same time another 

 small 10-armed specimen from station 4107 was recorded which is regarded herein as the. 

 type specimen of Stiremetm decora (see page 134). In 1909 crassicirra was removed 

 to the new genus Cosmiometra. It has not been rediscovered since it was originally 

 described. 



