PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 301 



Slightly spiny indi\aduals only were found at stas. 4361, 4534, 3205, 2866, 3343 

 and 3458, from Puget Sound to San Diego in from 166 to 943 meters, the temperatures 

 ranging from 6.22° C. to 7.44° C. 



Ahnost smooth specimens only were dredged at stas. 3347, 3071, 3070, and at 

 Loring, Alaska. The localities are from Washington to Loring, Alaska, in shallow 

 water to 1251 meters, the temperatures ranging from 3.28° C. to 4.95° C. 



Apparently the tendency to develop spines increases with the increasing tempera- 

 ture of the habitat. 



In the type specimen of serratissima, from Albatross sta. 3464, the centrodorsal 

 is hemispherical. 



The cirri are XL-L, about 36, 30 mm. long; the segments show a tendency to over- 

 lap, and almost all of them bear strong dorsal spines. 



The radials are concealed. The IBri are barely visible. The IBr2 (axillaries) 

 are very short and broad. 



The 10 arms are 105 mm. in length. The ossicles of the IBr series and proximal 

 brachials are thickly set with small sharp spines; the brachials have overlapping distal 

 edges set with numerous small sharp teeth. 



Syzj'gies occur between brachials 3 + 4, 9 + 10, 16 + 17, and distally at intervals 

 of 3 muscular articulations. 



Pi is from 17 to 21 mm. long with 45 to 60 short segments, and bears a long comb 

 distally. P2 is longer than Pj, from 18 to 22 mm. in length with 45 to 60 segments. 

 P3 may be 20 mm. long with 36 segments resembling P2, or it may be 12 mm. long 

 with elongated segments like P4. The distal pinnules are long and slender, the seg- 

 ments \vith overlapping spinous distal edges. 



In the very brief original description Antedon perplexa was merely said to be in 

 general similar to asperrima but more slender with the brachials longer and wedge- 

 shaped, the axiUary considerably wider than the IBr,, and the third syzygy almost 

 invariably between brachials 16+17, rarely between brachials 15 + 16, and never 

 between brachials 14 + 15. 



Ziesenhenne (1937) gives the color in hfe of serratissima as reddish brown, the 

 pinnules dark brown to black, the cirri light brown. 



Abnormal specimens. — With 9 arms: A specimen labeled merely as from the 

 western coast of North America (U.S.N.M., 35827) has 9 arms. The arms are about 

 150 mm. long. On one ray the two elements of the IBr series are slightly smaller than 

 on the others and are followed by two fu-st brachials and each of these by a second 

 brachial which, though smaller than those on the other rays, are normal. The two 

 second brachials are followed by a single first syzygial pair of the normal size in the 

 shape of an inverted axLUary, which is succeeded by a normal undivided arm. The 

 two first brachials are just in contact over the anterior angle of the axillary, and the 

 second brachials are more broadly in contact beneath the angle of the inverted axillary. 

 A small pore passes in between the fused portions of the two fu-st and two second 

 brachials. 



The conditions in this individual are very similar to those in the 9-armed speci- 

 men of Ileliometra glacialis described by Levinsen (vol. 1, part 2, pi. 37, fig. 1231); 

 but the elements following the two second brachials are single and the arm base is not 

 so much enlarged. 



