24 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



DAIDALOMETRA EURYMEDON. up- ov. 



Diagnostic features. The cirri are short, considerably less than half the length of 

 the arms, with 32-39 segments; the carination of the division series and arm bases is 

 low, with a rounded crest; and the proximal and distal borders and the lateral edges of 

 the elements of the division series and first two brachials are sparsely spinous or tuber- 

 cular. The 10 arms are about 65 mm. long, and the cirri are up to 24 mm. long. 



Description. The centrodorsal is conical, with the truncated apex bearing in the 

 center a group of six long blunt spines, of which one is centrally situated and the other 

 five are radially placed about it. The cirrus sockets are arranged hi 10 columns of 

 usually 2 each. The two columns in each radial area are more or less separated proxi- 

 mally in the midradial line, but are hi contact apically. The columns are everywhere 

 closely crowded against each other interraclially. 



The cirri are XX, 32-39, up to 24 mm. in length. The first segment is very short, 

 the second is longer, the third is from twice as broad as long to slightly longer than 

 broad. In the longest cirri the fourth segment is as long as, or slightly longer than, 

 broad, and the fifth is a transition segment, from two and one-half to three times as 

 long as the median width. The segment following is of about the same length, slightly 

 longer or slightly shorter, and those succeeding decrease hi length so that the segments 

 in the outer half of the cirri are about as long as broad, becoming more or less longer 

 than broad distally. In the shorter cirri the fourth is the transition segment. The 

 midventral line of the first four segments and of the proximal portion of the transition 

 segment is more or less narrowly gabled, though never sharply carinate. The distal 

 dorsal edge of the transition segment is slightly produced. This production of the 

 dorsal portion of the distal edge slowly increases hi amount, and in the outer quarter 

 of the cirri becomes a high carinate dorsal spine. 



The radials are rather long, being about three times as broad as the median length. 

 The distal border is everted and more or less irregular, and there is a high and abrupt 

 narrowly rounded median keel or tubercle. The IBrj are about four times as broad as 

 the median length. The lateral borders are hi contact, and the anterolateral angles 

 are sharply cut away. The median portion rises into a sharply rounded median cari- 

 nation which is very distinct, though much lower than that on the radials, and the 

 lateral portions of the distal border bear usually two conspicuous short blunt spines 

 or tubercles. The IBr 2 (axillaries) are rhombic, nearly twice as broad as long, with a 

 prominent thin lateral flange under each of the lateral angles, a roundedly carinate 

 elevation hi the proximal half or two-thirds corresponding to that on the IBri, and a 

 few blunt spines or tubercles on the proximal border just above those on the distal 

 border of the IBr^ 



The 10 arms are about 65 mm. long. The first two brachials bear a narrow flange 

 on the outer side by which they are just in contact. The first brachials may have 

 minute denticulations on the distal border. The earlier brachials are rather abruptly 

 rounded in the middorsal line, this feature being most marked on the first two ; but they 

 can scarcely be called carinate. The brachials in the outer half of the arm have the 

 median portion of the distal edge greatly produced and tipped with a comb of spines, 

 so that the dorsal profile of the outer half of the arms is very strongly serrate. 



