752 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



The second brachials are irregular in shape, with a strong rounded posterior projection. 

 The third and fourth brachials, which together form the first syzygial pair, are together 

 about half again as long as broad. The following brachials are rather longer than 

 broad, gradually becoming more elongate and in the outer part of the arm reaching 

 a length of about three times their width. The brachials are all remarkable for their 

 strong central constriction and large and expanded ends which, from the sixth brachial 

 onward, bear a fringe of rather large spines. 



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

 tervals of 2 muscular articulations. 



P! is very slender and filiform; the first three segments are about as long as broad, 

 strongly concave dorsally with prominent ends; the following segments rapidly become 

 elongated with broadly flaring distal ends. The tip of the pinnule is broken. P 3 

 and the following pinnules bear large gonads on the fifth to seventh segments, which 

 are slender and much elongated. The distal pinnules are exceedingly slender with 

 the first segment nearly as long as broad, the second about twice as long as broad, 

 wider proximally than distally, and the remainder very slender and greatly elongated 

 with expanded ends. 



Locality. Albatross station 2761; off the coast of Brazil, east of the Abrolhos 

 Islands (lat. 1539'00" S., long. 3832'54" W.); 1495 meters; temperature 3.89 C.; 

 pteropod ooze; December 26, 1887 [A. H. Clark, 1908] (1, U.S.N.M., 22671). 



Remarks. As yet this species is known only from the single specimen which was 

 originally described under the name of Bathymetra minutissima in 1908 and transferred 

 to the genus Trichometra in 1918. 



[NOTE BY A.M.C.] Mr. Clark himself altered the typescript to include this species 

 in the genus Thaumatometra, presumably concluding that, even allowing for the very 

 small size, the much longer but many fewer cirrus segments preclude its inclusion in 

 Trichometra but ally it with Thaumatometra. 



THAUMATOMETRA SEPTENTRIONALIS A. H. Clark 



[See vol. 1, pt. 2, fig. 759, p. 353] 



Thaumatometra, sp. A. H. CLARK, Die Crinolden der Antarktis, 1915, p. 147 (undescribed species 

 from the region southwest of Iceland). 



Thaumatometra borealis A. H. CLARK, Die Crinolden der Antarktis, 1915, p. 144 (north Atlantic 

 species) (nomen nudum}. KOEHLBR, Les e'chinodermes des mers d'Europe, vol. 2, 1927, p. 133 

 (women nudum). 



Thaumatometra septentrionalis A. H. CLARK, Unstalked crinoids of the Siboga-'Exped., 1918, p. 256 

 (in key; range), p. 258 (references; description in press); The Danish Ingolf-Exped., vol. 4, No. 5, 

 Crinoidea, 1923, p. 12 (description; sta. 18), p. 43 (range), p. 58 (stas. 11, 36), p. 56 (in key). 

 MORTBNSEN, Handbook of the echinoderms of the British Isles, 1927, p. 26; Medd. Gr0nland, 

 vol. 79, No. 2, 1932, p. 50 (range) . TORTONESE, Bull. Inst. Oceanogr. Monaco, No. 956, 1949, 

 p. 4 (bathymetrical range). 



Diagnostic features. The cirri are about XXX, with about 10 segments, of which 

 the longest are six times as long as broad, the antepenultimate is twice as long as broad 

 and the penultimate little, if at all, shorter; when the arms are about 15 mm. long the 

 cirri are 6 mm.; the segments of the proximal pinnules are long, the third one of PI 

 being already twice as long as broad. 



