PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS G83 



Bathymetrical ranrje. — From 1089 to 3426 meters. 



Remarks [by A.M.C.]. — A comparison of the two Southern Ocean species Tonro- 

 metra remota (P. H. Carpenter) and Florometra spinulifera John (subfamily Heliomet- 

 rinae) leads me to the conclusion that the two are congeneric. Both liave cirri with 

 the longer segments flared and the distal ones with rounded dorsal processes, division 

 scries of comparable form, the centrodorsal of similar proportions with the sockets 

 tending to bo arranged in columns and broad-based oral pinnules tapering markedly 

 at first but attenuated and prolonged in the outer part. I found it hard to decide 

 whether spinulifera should be referred to Tonrometra, or remota to Florometra. The 

 relatively small numbers of cirrus and pinnule segments compared with those found 

 in most species of Florometra might bo explicable by the relatively small size (40 to 60 

 mm. arm length) of the known specimens of the two species in question. On the other 

 hand the elongated outer segments of Pi would seem to preclude both of them from 

 inclusion in the Hehometrinao. The specimens of Florometra usually taken are almost 

 invariably larger, two of the smallest of F. m,awsoni in the British Museum (with the 

 exception of juveniles from the Ross Sea) having the arm length about 55 and 60 nam. 

 with the widths at the first syzygy 1.2 and 1.4 mm. The middle segments of Pj are 

 relatively a Uttle longer than in larger specimens of F. mawsoni but are still not more 

 than twice as long as wide (fig. 40,e, p. 686) and the distalmost segments are again 

 shorter and more flared in shape, quite unlike the long cyhndrical outer segments in the 

 two species in question. Florometra mawsoni itself is also marked off from remota and 

 spinulifera by the very sharp distal edges of the cirrus segments. With the present 

 material it seems best to refer spinulifera to Tonrometra. 



KEY TO THE SPECIES OF TONROMETRA 

 [by A.M.C] 

 a'. Segments of the oral pinnules expanded and spinous at the ends; longest cirrus segments not more 

 than half again as long as their median widths; East Indian area. 



6'. Cirri about XXX, 18-20 (Molucca Islands; 1089 meters) brevipes (p. 683) 



b'. Cirri XL-L, 25-33 QesserSunda Islands; 1280 meters) multicirra (p. 684) 



a-. Segments of the oral pinnules straight, not expanded or notably spinous at the ends; longest cirrus 

 segments twice or more their median width in length; Southern Ocean, 

 b'. Cirri with up to 37 segments, the longest of which are two and a half times their median width 



(off Princess Elizabeth Land, Antarctic; 1266 meters)... spinulifera (p. 686) 



6^. Cirri with up to 30 segments, the longest of which are twice as long as their median width (be- 

 tween Marion Island and the Crozet Islands and near the South Orkney Islands; 2925 and 

 3426 meters) ..remota (p. 688) 



TONROMETRA BREVIPES (A. H. Clark) 



Trichometra brevipes A. H. Clark, Notes Leyden Mus., vol. 34, 1912, p. 147 (description; Sihoga 

 sta. 150); Die Crinolden der Antarktis, 1915, p. 145 (comparison with T. remota). 



Tonrometra brevipes A. II. Clark, Journ. Washington Acad. Sci., vol. 7, 1917, No. 5, p. 130 (listed); 

 Unstalked crinoids of the Siboga-E\pc6., 1918, p. 258 (in key; range; detailed description; sta. 

 150), p. 273 (listed), pi. 26, fig. 92. 



Diagnostic features. — The cirri arc about XXX, 18-20, the longer segments not 

 longer than their maximum diameter; P, with all but the first few segments greatly 

 elongated and with expanded and finely spinous joints. 



Description.— The centrodorsal is low conical, twice as broad at the base as high. 

 It bears about 30 closely crowded and irregularly placed cirrus sockets which have very 

 prominent rims. 



