794 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



At the Museum of Comparative Zoology in the summer of 1907 Dr. W. McM. 

 Woodworth, in looking over some marine worms from Blake station 205, discovered a 

 much mutilated example of a species of Pentametrocrinus, which he showed to me. 

 Presumably the species represented is P. atlanticus, though the condition of the specimen 

 is such that accurate identification is not possible. This individual was taken in 1879, 

 and was therefore the first actually dredged. Having this capture in mind, I added 

 "West Indies" to the distribution of the "Eudiocrinidae" (Pentametrocrinidae) given in 

 a paper published in 190S (Proc. U.S. Nat. Mus., vol. 34, p. 210), and also added 

 "West Indies" to the known habitat of P. atlanticus in 1911. 



In 1913 I recorded this species from 3 of the Helga stations off the western coast 

 of Ireland. 



In 1928 Gislen reexamined one of the Helga specimens in the British Museum and 

 published a brief note on it. 



PENTAMETROCRINUS DIOMEDEAE A. H. Clark 



[See vol. 1, pt. 1, fig. 130, p. 187] 



Eudiocrinus japonicus (part) A. H. CLARK, Proc. U.S. Nat. Mus., vol. 32, 1907, p. 571 (Albatross 

 sta. 4934). 



Pentametrocrinus japonicus (part) A. H. CLARK, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 135. 



Pentametrocrinus diomedeae A. H. CLARK, Proc. U.S. Nat. Mus., vol. 34, 1908, p. 319 (Japan; listed; 

 nomcn nudum); Smithsonian Misc. Coll., vol. 52, pt. 2, 1908, p. 234 (Albatross sta. 4934; also 

 5173); Crinoids of the Indian Ocean, 1912, p. 250 (synonymy; localities); Journ. Washington 

 Acad. Sci., vol. 5, No. 6, 1915, p. 215 (Malayan type; range and its significance); Unstalked 

 crinoids of the Sz&oga-Exped., 1918, p. 261 (in key; range; notes; sta. 95), p. 272 (listed); Smith- 

 sonian Misc. Coll., vol. 72, No. 7, 1921, pi. 14, fig. 50. GibL^N, Zool. Bidrag Uppsala, vol. 9, 

 1924, pp. 26, 39, 41, 42, 44, 46, 83 (articulations), p. 283 (length of the ambulacral groove); 

 fig. 11, p. 45 (arm base); fig. 90, p. 81; fig. 116, p. 93; figs. 189-191, p. 98; Vid. Medd. Nat. Foren. 

 K0benhavn, vol. 83, 1927, p. 3 (stas. 7, 24), p. 52 (stations; notes), p. 68 (listed); figs. 45-46, 

 p. 44; Ark. Zool., vol. 19, No. 32, 1928, p. 12; Lunds Univ. Arsskr., new ser., Avd. 2, vol. 30, 

 No. 11, 1934, p. 17. 



Pentametrocinus diomediae GISLEN, Vid. Medd. Nat. Foren. K0benhavn, vol. 83, 1927, p. 69. 



Diagnostic features. The lowest pinnule is on the epizygal of the first syzygial 

 pair, Br 6 ; the centrodorsal is conical, bearing XXX-LX cirri which in length equal 

 about a fifth the length of the arms and which are moderately stout, strongly recurved 

 in the outer portion, composed of 15 to 19 segments, of which the longest is about 4 times 

 as long as broad and the distal are shorter; the terminal claw is prominently hooked; 

 and the arm bases are rather robust, though not rugged, the articular tubercles being 

 obsolete; the proximal pinnules have over 20 segments. 



Description. -The centrodorsal is conical with the sides gently convex, 4 mm. 

 broad at the base and 3 mm. high. The cirrus sockets are closely crowded, arranged 

 roughly in two or three, with sometimes a partial fourth, rows; about the periphery of 

 the centrodorsal there are usually four sockets beneath each radial. 



The cirri are XL-LX, 14-17 (usually 15-17), from 15 to 20 mm. long. The first 

 segment is short, the second is about as long as broad, the third is about twice as long 

 as broad, the fourth is about three times as long as broad, and the fifth to seventh are 

 about four times as long as broad; the following segments gradually decrease in length 

 so that the antepenultimate is about twice as long as broad and the penultimate about 

 as long as broad. The cirri do not taper distally, but the penultimate segment is less 

 broad than that preceding it. The terminal claw is considerably longer than the 



