734 PROCEEDINGS OF THE NATIONAL MUSEUM. volxxxii. 



smooth rods with rounded tips. Color in life, two phases, one dark 

 purple, the other pale lilac; wheel papilhe whitish; tentacles brownish. 

 Length, about 150 mm.; breadth variable, in unconstricted state, 7 to 

 9 mm. 



Locality. — Station 3892, north coast of Molokai Island, 328 to 414 

 fathoms, line gray sand; bottom temperature 42. 5'" ; 10 specimens. 



Type.— Csit. No. 21229, U.S.N.M. 



The present species is much larger than the foregoing and differs in 

 the great reduction in number of wheel papilhe as well as in color. 

 The wheel papillas vary greatly in number and apparentl^^ are more 

 numerous in the light than in the dark individuals, which have in the 

 neighborhood of ten papilhe, mostl}^ in posterior two-thirds of body. 

 In only one case have I found a papilla outside of the middorsal inter- 

 ambulacrum. In one individual a small papilla is situated just at the 

 upper edge of a dorso-lateral interambulacrum and is nearly radial in 

 position. Inasmuch as the body is constricted at intervals it is not 

 possible to tell the exact breadth. Tentacles are much contracted in 

 preserved specimens. The proximal digits are often so small that it 

 is then difficult to tell whether there are 8 or 10 digits. The prevalent 

 number appears to be 12 or 11. The terminal digits are only slightly 

 larger than the subterminal, although in an uncontracted state the 

 difference may be greater. 



The calcareous ringis sufficiently shown by the figure (Plate LXXXII, 

 fig. 5c). There are five Polian vesicles, of which two are much larger 

 than the other three. Madreporic canal single, in dorsal mesentery. 

 Tubules of gonad unbranched. Retractor muscles rather stout, con- 

 fluent with longitudinal bands about 15 mm. from anterior extremity 

 of body. 



Wheels from same individual do not difl'er so much in size as in 

 liavKulensis., and are larger than in that species. They varj'- from 

 about 0.12 to 0.19 mm., the majority being al)out 0.175 mm., in 

 diameter. The rods are commonly about 0.08 to 0.12 mm. long, while 

 the smooth ones in the muscles vary from 0.041 to 0.08 mm. Most 

 of the rods of outer perisome have one to throe shallow notches at tip, 

 and occasionally a short branch in the center. Somewhat deformed 

 grains such as X, fig. 3(2, are rarely seen, but real C-shaped rods 

 appear to be absent. The deposits are rather evenly scattered, but 

 appear to be lacking in tentacles. 



This species differs from the other 12-tentacled forms in the distri- 

 bution of the wheel papillae, of which there are a veiy small number, 

 confined to middorsal interambulacrum. Ir respect to the small num- 

 ber of wheels, at least, uniserialls resembles Trochodota j^urj^mrea"' 



•^Not to be confused with Sigmodota purpurea Studer {Chiridota studeri Th^el), 

 which has S-shaped deposits, and which has been considered as a synonym of Chvi- 

 dota contoria Ludwig, a Tseniogyrus. 



