PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 537 



cinna but have examined the holotypes of the other four species assigned to this 

 genus. In two of these, hirsuta and/rasm, the interradial cirrus sockets are arranged 

 in distinct columns but radially the sockets are quite irregular in position. In E. 

 aurora and even more so in E. marri the arrangement is still more irregular, and certainly 

 not indicative of the subfamily Zenometrinae. Mr. Clark had removed marri to the 

 Isometrinae on account of the slightly expanded segments of the genital pinnules and 

 the irregular arrangement of the cirrus sockets. However, a comparison of the holo- 

 type with specimens of Isometra showed that the expansion is relatively much less, even 

 for a male, than that found in Isometra and is much more comparable with the slight 

 expansion shown by Anthometra adriani of the subfamily Heliometrinae illustrated by 

 Dr. Dilwyn John (1938, fig. 5, p. 151). Indeed I think marri with its short cirrus 

 segments and short proximal segments of Pj cut away at the joints, would be very 

 similar to a precocious, stunted Heliometrin. However, it appears to have more in 

 common with Eumorphometra aurora than with any other antarctic comatulid, notably 

 the proportions and numbers of the cirrus segments. With only one specimen known, 

 it seems inadvisable to remove marri from the genus Eumorphometra. Possibly the 

 whole genus might be better removed from the Zenometrinae. Only the shorter and 

 more numerous cirrus segments and the higher and more conical centrodorsals seem 

 to distinguish its species from those of the antarctic Phrixometra of the Bathymetrinae 

 which also has viviparous species. Besides the more or less irregular arrangement of 

 the cirri, these are fixed to the centrodorsal much more firmly than in most species of 

 the Zenometrinae, as an attempt to detach some of the stumps in the types oijraseri, 

 marri, and aurora has shown. 



KEY TO THE SPECIES OF EUMORPHOMETRA 



[by A.M.C.] 



a 1 . Peripheral cirri with 34-40 segments (South Shetland Islands; 410-440 meters) ...fraseri (p. 537) 

 a 1 . Peripheral cirri with not more than 30 segments. 



6'. Axillary with very slight proximal angle, the distal edge of the IBr, almost straight; division 

 series flared but not conspicuously spinous at their distal edges (near Marion Island; 256 



meters) hirsuta (p. 540) 



b*. Axillary rhombic with a distinct proximal angle more or less incising the distal edge of the IBr,; 



division series usually with spinous edges. 

 c 1 . Only XXX cirri when the arm length is 30 mm.; PI only 2 mm. long with about 9 segments 



(shores of Antarctica near Gaussberg; 380-400 meters) concinna (p. 542) 



c 3 . XL or more cirri when the arm length is 25-30 mm.; P! 4-4.5 mm. long with 13-14 segments. 



d l . Three or four basal segments of PI not longer than broad, segments of the genital pinnules 



slightly expanded alongside the gonads (Clarence Island, South Shetlands; 490-610 



meters) marri (p. 544) 



d 1 . Second and following segments of PI more or less longer than broad, segments of genital 

 pinnules not expanded (Shag Rocks near South Georgia and off Enderby Land, Antarc- 

 tica; 177-220 meters) aurora (p. 547) 



EUMORPHOMETRA FRASERI John* 



FIGURE 29,<z,6 



Eumorphometra fraseri JOHN, Discovery Reports, vol. 18, 1938, p. 123 (listed), p. 129 (range), p. 155 

 (description; Discovery Investigations sta. 1955), pi. 4, fig. 2, text-fig. 7, a-e, p. 155. 



'See also Addenda (p. 837) under 1963. 



