PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 621 



c 2 . Cirri XXVI-XLIII, 28-41; in the female only the third and fourth (rarely also the fifth) 

 segments of the genital pinnules are expanded; a species of moderate size, the length from 

 IBri to Br t (inclusive) being 8-10 mm. in most specimens (from Graham Land, Bransfield 



Strait and the Ross Sea; 130-567 meters) graminea (p. 627) 



a 2 . Pj smaller than P,. 



b 1 . The first genital pinnule is usually P 6 or P (rarely P< or Pj). 



c 1 . The division series and proximal brachials with a distinct keel in the dorsal midline; longest 

 cirrus segments about twice as long as wide, constricted in the middle and flared at the 

 distal ends (from off Enderby and MacRobertson Lands, 50-60 E.; 209-300 meters). 



johanni (p. 629) 

 c 2 . No keel on the division series and proximal brachials; cirrus segments not constricted in the 



middle and the longest ones not much longer than wide. 

 d 1 . PI with about 9 segments when the length IBri to Br 9 (inclusive) is 9 mm. (known from off 



Uruguay; 1097 meters) challenger! (p. 631) 



d 2 . PI with about 12 or 13 segments when IBri to Brg (inclusive) is about 9 mm. (from off the 

 southern tip of Brazil to the Falkland-Magellanic region and the northwest Weddell Sea; 



79-242 meters) vivipara (p. 632) 



b 2 . The first genital pinnule is usually P 8 or sometimes P 4 (known from the Shag Rocks west of South 

 Georgia; 177 meters) flavescens (p. 644) 



ISOMETRA ANGUSTIPINNA (P. H. Carpenter) 



Antedon, sp. P. H. CARPENTER, Proc. Roy. Soc., vol. 28, 1879, p. 384 (Challenger sta. 320). 



Antedon angustipinna P. H. CARPENTER, Challenger Reports, Zool., vol. 26, pt. 60, 1888, p. 189 (de- 

 scription; sta. 320), pi. 29, figs. 1-4. A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 

 1907, p. 353 (listed). HAMANN, Bronn's Klassen und Ordnungen des Tier-Reichs, vol. 2, Abt. 

 3, 1907, p. 1579 (listed). 



Isomctra angustipinna A. H. CLARK, Proc. Biol. Soc. Washington, vol. 21, 1908, p. 133 (listed), p. 134 

 (the young of Antedon lineata); Smithsonian Misc. Coll., vol. 61, No. 15, 1913, p. 64 (published 

 references to specimens in the B. M.; Challenger sta. 320); Journ. Washington Acad. Sci., vol. 5, 

 1915, No. 3, p. 81 (Antarctic; range); Die Crinoiden der Antarktis, 1915, p. 105 (Antedon hirsuta 

 of Andersson, not of Carpenter, near this species; collected by the Challenger and recorded as 

 Antedon lineata + A. angustipinna), p. 107 (in key to antarctic crinoids), p. 146 (synonymy; 

 localities), p. 168 (shallow water antarctic type; Magellanic), p. 192 (further discussion). 

 MORTENSEN, Vid. Medd. Nat. Foren. K0benhavn, vol. 68, 1917, p. 208 (compared with I. vivi- 

 para); Wiss. Ergeb. schwed. Sudpolar-Exped. 1901-1903, vol. 6, Lief. 8, 1918, pp. 13, 14 (com- 

 pared with /. vivipara); Studies in the development of crinoids, 1920, p. 31. A. H. CLARK, The 

 Danish 7n<7o(f-Exped., vol. 4, No. 5, Crinoidea, 1923, p. 42 (range). GISLEN, Ark. Zool., vol. 19, 

 No. 32, 1928, p. 11 (pinnules). JOHN, Discovery Reports, vol. 18, 1938, p. 124, pp. 177, 178 

 (redescription of type specimen; distinct from lineata); fig. 14, p. 177. 



Diagnostic features. The cirri are about XXX, with probably up to 30 segments, 

 of which most are flared and the distal ones have a dorsal keel; the first two pinnules 

 are small and similar, with about 6 segments in the unique holotype, but P 9 may be a 

 genital pinnule, in which case it is more than twice the length of PI. 



Description (from John, 1938). The arms are all broken but were probably about 

 25 mm. long when complete. The length IBr, to Br 9 (inclusive) is 7 mm. and the width 

 at the first syzygy (3+4) is 11 mm. 



The centrodorsal is low conical and is almost completely covered by the cirri which 

 number about XXX. The longest remaining cirrus has 27 segments but appears to be 

 immature, according to Dr. John; an apparently mature one with 22 segments has the 

 third to eighth segments longer than broad. The distal ones become shorter, about as 

 long as broad with a slight dorsal keel. Most of the segments are flared at the distal 

 end. The opposing spine is large and the terminal claw curved. 



