826 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



does not state bow far up on the centrodorsal these cirri are placed. Their second 

 segment is ah'ead}^ twice as long as wide and the sixth is five times as long as its median 

 width, being somewhat expanded at the ends. This specimen has the centrodorsal 

 "rather more than 3 mm." in height and "less than 3 mm." in basal diameter. The 

 six cirrus segments together measure up to 9 mm. in length. 



The disk may bear a few minute calcareous granules on its ventral surface and also 

 on its sides between the post-radial series; in other specimens it is nearly or quite naked. 

 The mouth is somewhat excentric and is surrounded by a large peristome. Near the 

 mouth is the anal tube, which also is slightl.y excentric in position. 



The basal ring is a very thin circlet of plates. Exteriorly the basals are visible as 

 very low triangles; interradially they are somewhat elevated and may form prominent 

 tubercles upon the inteiTadial ridges of the centrodorsal. In the young the basals 

 are relatively larger, externally forming a broad ring of nearh' uniform height (0.5 mm.) 

 all around the calyx, and rising only very slightly in the interradial angles where, however, 

 they project outward somewhat. With advancing age the radial portion of the basals 

 becomes more and more narrow until finally it is visible only as a narrow line connecting 

 the interradial triangles, which, with the decrease in the height of the radial portion 

 of the basals, become more marked. 



The radials are short and dorsally nearly flat in the fully growTi, but longer, often 

 half as long as broad, in the young. 



The IBri are about twice as broad as long in the larger individuals, with the distal 

 border but little incised. The sides are straight. In smaller specimens thej^ are about 

 as long as broad and often have the distal border considerably incised. The IBro (axil- 

 laries) are pentagonal in the larger specimens and sometimes as much as tvrice as long 

 as the IBn with little, if any, backward projection; but in the smaller specimens they 

 are more and more rhombic, about as long as broad, with a strong proximal projection. 

 The distal sides are concave and the distal angle is truncated at the tip. 



The 10 arms are seldom preserved much beyond the first few sj-zygies. The fiist 

 brachials are wedge-shaped, interiorly separated at the base by the truncated distal 

 angle of the axillary. The second brachials are quadrate, with the distal border very 

 oblique. The sjmarthrial articulations between the elements of the IBr series and the 

 first two brachials rise to a low more or less pronounced tubercle. The first svzygial 

 pair (composed of brachials 34-4) is very obliquely wedge-shaped with the inner side 

 much longer than the outer. The following brachials have very oblique ends and 

 markedly unequal sides; they are at fii-st slightlj' broader than long, but after about the 

 seventeenth they become longer than broad, and in the middle of the arm nmch longer 

 than broad. The distal part of the arm is unknown. In cross section the division 

 series and proximal brachials are more or less cylindrical but their sides may be somewhat 

 flattened. 



Syzygies occur between brachials 3 -(-4 and then at intervals of from 2 to 7 (usu- 

 ally from 2 to 4) muscular articulations. 



The lowest pinnule is almost always on the seventeenth brachial (the twelfth 

 brachial of Carpenter), exceptionally as early as the thirteenth brachial (the tenth 

 brachial of Carpenter). It is about 3.5 mm. long and is composed of about 12 segments, 

 of which the first is short, the second is somewhat longer than broad, and those follow- 

 ing become progressively elongated. The pinnules immediately succeeding appear 

 to be similar, but the first segment is shorter and more crescentic, and the second is 



