36 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



there are 19 septa. The ninth brachial (second hypozygal) has 19 septa, and the 

 fifteenth (third hypozygal) has 17 septa. 



Psathyrometra mreni. In a specimen with the arms about 60 mm. long the third 

 brachial has 16 septa, of which 11-12 are complete; the areola is narrow and indis- 

 tinct; the degree of strength is 1; there is one indistinct concentric synapticula. The 

 ninth brachial (second hypozygal) has about 16 very low septa. 



Poliometra prolixa. In a specimen with arms about 100 mm. long the third 

 brachial has 21-22 septa, of which 13 are complete; the areola is ventrally in broad 

 contact with the smooth ventral part of the ossicle, dorsally narrow and indistinct; 

 the joint face is somewhat undulating; the degree of strength is 2. In another case 

 there are about 22 septa. The ninth brachial (second hypozygal) has 21 septa, and 

 the ninteenth (third hypozygal) has 18 septa. 



Hathrometra tenella var. sarsii. In a specimen with an arm length of about 50 

 mm. the third brachial has 22 septa, including 9 complete septa and 2 ventral beams; 

 there is no areola; the degree of strength is 3. In another case there were also 22 

 septa. The ninth brachial (second hypozygal) in two cases had about 18 septa. 

 The fourteenth brachial (third hypozygal) in two cases had 18 and 19 septa; the degree 

 of strength was 2-3. 



PENTAMETROCRINIDAB 



Pentametrocrinus diomedeae. In a specimen with the arms about 100 mm. long the 

 distal face of the fourth brachial (first hypozygal) had 18 septa, including 11 complete 

 septa and 2 ventral beams; the areola was scarcely indicated; the degree of strength 

 was 2-1. The ninth brachial had 16 septa. 



Thaumatocrinus jungerseni. In a specimen with the arms about 70 mm. long 

 the distal face of the fourth brachial (first hypozygal) had 11 septa, including 5-6 

 complete septa and 1 ventral beam; there was no areola; the degree of strength was 2-3. 

 The ninth brachial (second hypozygal) had 11 septa, including 2 ventral beams. 

 The sixteenth brachial (third hypozygal) had 11 septa, including 5 complete septa 

 and 2 ventral beams. 



ATELECHINIDAE 



Atelecrinus helgae. In a specimen with an arm length of perhaps 90 mm. the 

 third brachial had 10-11 septa, including one broad ventral beam with a small ventral 

 pit, about 10 complete and finished or interrupted very narrow septa, four of them 

 tubercles only, and 3 ventral tubercles continuous with the ventral smooth part of 

 the ossicle; there was no areola; the degree of strength was 2-3. The seventh brachial 

 (second hypozygal) had 12 septa, including 11 very narrow and rather complete 

 septa and one ventral beam. The degree of strength is 2. 



Atopocrinus sibogae. Gisle"n said that if the author's statement that two small 

 ventral muscle bundles occur in the syzygies of this species can be verified this species 

 presents syzygial unions of a very interesting and ancient type, reminding one of the 

 oldest articulate type. He has, however, never been able to find any trace of rudi- 

 mentary muscles in ligamentary articulations in sections through arms of young comat- 

 ulids, in regenerating arms, or in ligamentary unions in Ptilocrinus pinnatus, Rhizo- 

 crinus Iqfotensis, or Ilycrinus carpenterii. Until it has been verified, he wrote, he 

 prefers to regard the statement with some reservation. 



