82 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



membrane really passed from one side to the other or not. For the most part indefi- 

 nitely bounded sheets of skeletal substance lay on both sides of the free central ambu- 

 lacra! groove, among which the sacculi lie uncovered, or through which they may be 

 seen. 



Hartlaub said that the disk in the two larger specimens is 6 mm. in diameter and 

 naked and incised. In his remarks on the three specimens he said that the arm lengths 

 were apparently 50, 45, and about 20 mm. 



The color in alcohol is white and whitish gray, with the disk and ambulacral 

 grooves brown or brownish. 



Notes. Count Pourtales's original description was as follows: 



Ten arms; centrodorsal plate flat, rather large, bearing about fifteen cirrhi on its circumference. 

 Cirrhi of about 20 joints, shorter than their diameter; all except the 3 or 4 first ones provided with 

 a short spine on the concave side; last joint with a claw, and penultimate with an opposing spine. 

 First radial protruding from the centrodorsal plate; second radial [IBn] nearly as long as broad; 

 radial axial [IBr2] pentagonal. First brachials nearly square, barely in contact by their lower 

 corners; second brachial with a large socket for the first pinnule, which is twice as long and more 

 than twice as thick as the second; of its 9 or 10 joints the 4th is remarkably long, forming about one 

 fourth of the total length; the other pinnules are rather short, and are formed of the same number of 

 cylindrical joints. Joints of the arms smooth, oblique, edges not prominent. Seven or eight joints 

 form a syzygium. 



One specimen only was dredged in 35 fathoms, west of the Tortugas. The spiny cirrhi make it 

 resemble Antedon (Comatula) Milberti Muller, said to be from North America, but the other charac- 

 ters do not agree. 



Hartlaub said that Pourtales's description of the cirri agreed with his observa- 

 tions on the three specimens he studied; but the IBr! are not "nearly as long as broad," 

 and the IB r 2 (axillaries) are more rhombic than hexagonal [Pourtales said pentagonal] 

 as Pourtales gave them. 



The two specimens recorded by Dr. Hubert Lyman Clark from off Little Cat 

 Island, Bahamas, have the arms 50 mm. long and the disk about 3 mm. across. 



The specimen recorded by the author from Barbados is very small with the arms 

 15 mm. long. 



Parasite. On one of the two large specimens examined by Hartlaub there was a 

 large myzostome cyst above PI of which the surface showed a plating of small cal- 

 careous plates. 



Localities. Bibb station 84P, 87P, or 88P ; west of the Dry Tortugas (lat. 2440'30" 

 to 24 43' 30" N.,long. 83 15' 00" to 83 30' 30" W.); 64 meters; January 16, 1869 

 [Pourtales, 1869; P. H. Carpenter, 1879, 1883, 1888; Bell, 1882; Hartlaub, 1912; 

 A. H. Clark, 1923]. 



Blake; Florida Straits [Carpenter, 1888; Hartlaub, 1912; A. H. Clark, 1923]. 



University of Iowa's Bahamas expedition station 74; off Little Cat Island, Ba- 

 hamas; 5-24 meters; 1893 [H. L. Clark, 1918; A. H. Clark, 1923] (2, M. C. Z., 750; 

 U. I. M.). 



University of Iowa's Barbados-Antigua expedition station 1 1 ; Barbados [A. H. 

 Clark, 1921, 1923] (1, U. I. M.). 



No locality [Hartlaub, 1912]. 



Geographical range. From the Florida Straits and the Bahamas southward to 

 Barbados. 



Bathymetrical range. Sublittoral and down to 64 meters. 



