PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 631 



Localities. B.A.N.Z.A.R.E. station 40; off Enderby Land Gat. 6612' S., long. 

 4937' E.); 300 meters; January 17, 1930 [John, 1939] (1 female, the holotype and 

 1 male, B.AL; 2 females, 1 immature, Austr. M.). Type locality. 



B.A.N.Z.A.R.E. station 41; off Enderby Land Qat. 6548' S., long. 5316' E.) ; 

 180-209 meters; at 200 meters, temperature 1.77 C., salinity 34. 24/ 00 ; January 24, 

 1930 [John, 1939] (1 male, Austr. M.). 



B.A.N.Z.A.R.E. station 107; off MacRobertson Land (lat. 6645' S., long. 6203' 

 E.); 219 meters; February 16, 1931 [John, 1939] (1 male, 1 juvenile, B.M.; 2 pen- 

 tacrinoids, Austr. M.). 



ISOMETRA CHALLENGERI (A. H. Clark) 



Antedon lineata (not Antedon linealus Pomel, 1887) P. H. CARPENTER, Challenger Reports, Zoology, 

 vol. 26, pt. 60, 1888, p. 183 (description; sta. 320), pi. 13, figs. 4, 5. HAMANN, Broun's Kluss. n 

 und Ordnungen des Tier-Reichs, vol. 2, Abt. 3, 1907, p. 1579 (listed). A. H. CLARK, Proc. U.S. 

 Nat. Mus., vol. 34, 1908, p. 480 (renamed challenger!) Proc. Biol. Soc. Washington, vol. 21, 

 1908, p. 134 (synonym of Isomelra anguslipinna). HARTLAUB, Mem. Mus. Comp. Zool., vol. 

 27, No. 4, 1912, pp. 398, 399 (compared with A. [Analcidomelra] armata). 



Antedon challengeri A. H. CLARK, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 353 (new name for 

 Antedon lineata P. H. Carpenter, 1888, not A. lineatus Pomel, 1887); Proc. U.S. Nat. Mus., vol. 

 34, 1908, p. 480 (same). 



Isometra lineata JOHN, Discovery Reports, vol. 18, 1938, pp. 174-176 (distinct from angiistipinna; 

 redescription of holotype) ; fig. 13, p. 176. 



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

 of which the longest are only slightly longer than broad; P 2 is slightly smaller than P,, 

 each having 8 to 9 segments; the first genital pinnule is P 6 or P 7 . 



Nomenclature [by A.M.C.]. Since Pomel's name Antedon lineatus for a fossil 

 invalidated by a year A. lineata of P. H. Carpenter, A. H. Clark substituted the name 

 challengeri in 1907, but the following year submerged the name in the synonymy 

 of angustipinna. However, John (1938), after re-examining both the type specimens, 

 decided that the species are, after all, distinct. I have accordingly modified the- 

 typescript. 



Description. The centrodorsal is almost completely hidden by the stumps of the 

 broken cirri. 



The cirri are about XXV, the longest with at least 30 segments and over 16 mm. in 

 length; they have a slight distal taper. The fifth segment is the longest, slightly 

 longer than broad; the segments in the terminal third of the cirri are broader than long. 

 All of the segments overlap slightly on the dorsal side and the outer gradually acquire 

 a faint dorsal keel with a rather prominent dorsal spine. 



The radials are partially visible. The IBr, are oblong, not united lateral!}', with 

 the distal border slightly excavated. The IBr 2 (axillaries) are pentagonal and some- 

 what broader than long. The elements of the IBr series are elevated in the middle 

 line, decreasing in height laterally. 



The 10 arms are about 90 mm. long. The first brachials are somewhat incised 

 by the second, which are relatively short and broad. The following brachials are 

 smooth and obliquely wedge-shaped, becoming rather elongated toward the arm tips. 



Syzygies occur between brachials 3+4, 9 + 10, and 14+15, and distally at intervals 

 of from 2 to 5 (usually 3 or 4) muscular articulations. 



The length from the IBr t to the second syzygy is 9.0 mm. and the width at the first 

 syzygy is 1.5 mm. 



