PART B A MONOGRAPH OF THE EXISTING CRINOIDS 621 



c'. 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 Brj (inclusive) being 8-10 mm. in most specimens (from Graham Land, Bransfield 



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



a'. Pii smaller than Pi. 



6'. The first genital pinnule is usually Pj or P» (rarely P, or Pr). 



c'. The division series and proximal brachials vnth 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'. 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'. Pi with about 9 segments when the length IBri to Brj (inclusive) is 9 mm. (known from off 



Uruguay; 1097 meters) challengeri (p. 631) 



(P. 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) 



6». The first genital pinnule is usually Pj or sometimes P4 (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). 



Anledon 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). 



laomelra 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 Crinolden der Antarktis, 1915, p. 105 (Anledon hirsula 

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

 Anicdon lineala+ 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 7. 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 Ingolf-Exped., vol. 4, No. 5, Crinoidea, 1923, p. 42 (range). — Gisl^n, 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 Jeatures. — 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 Pj may be a 

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



Description (from John, 1938). — The arms arc aU broken but were probably about 

 25 mm. long when complete. The length IBr, to Br, (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. 



