750 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



solution, and when added in quantity caused the absorption band to disappear. It 

 did not render the sohition at all green. 



Antedonin. — Moseley notes that the various species of comatulids appear to be 

 usually either of a rose color or of an orange or yellow, running into a yellow brown, 

 or of a dark purple. Both the rose or red and the yellow coloring matters are freely 

 soluble in alcohol, and usually in fresh wat«r. 



The colored solutions obtained from a large number of such species dredged 

 by the Challenger were examined, but none of them yielded a characteristic absorp- 

 tion spectrum showing bands. The European species have similarly been found to 

 yield a coloring matter free from bands. In the case of Antedon all the spectrum 

 but the red is absorbed. Moseley found a purple species occurring at Suez {Troplo- 

 metra audouini) to yield a similar spectrum. 



By dredging in from 8 to 12 fathoms in the channel between Somerset and 

 Albany Island at Cape York, Queensland, a comatulid (probably Coniatula 

 rotalana) was obtained in abundance which was of a dark purple color. The color- 

 ing matter was insoluble in glycerine, soluble to a large extent in fresh water, and 

 abundantly soluble in weak spirits, and gives an intense fuchsin-colored solution. 

 This, when compared with that obtained from a deep-sea holothurian found to con- 

 tain the same coloring matter, is seen to be much redder, but it becomes pinker on 

 dilution with alcohol, and at last quit* pink and indistinguishable to the naked eye 

 from that of the holothurian. 



The solution when of moderate strength gives a spectrum consisting of three 

 well-defined absorption bands. On using a very weak .solution and gradually 

 strengthening it the least refrangible band, being the most intense, appears first, 

 and is visible in solutions which appear very slightly tinted indeed to the unassisted 

 eye. The other two bands appear together. The mid(dle band is at first darkest 

 about E. The most refrangible band, which is much less dark than the middle one, 

 is of uniform intensity. Neither the red nor the violet ends of the spectrum are 

 much absorbed. 



When the solution is very strong all three bands become intense; the violet 

 disappears and all the light, except the red and yellow, becomes very faint. The 

 bands remain as before, except that the middle band now appears of uniform 

 intensity throughout. When the solution is rendereid stronger still the least 

 refrangible band extends gradually up toward D, and the whole of the spectrum 

 becomes absorbed except a band of light consisting of red with a little yellow. 



On the addition of hydrochloric acid to the alcoholic solution the color changes 

 to an orange, and the spectrum now consists of two bands, one lying to the red side 

 of E, the other to the violet side of h and extending to F. These bands are in weak 

 solutions separated by an interval of light. In very intense solutions the bands are 

 joined by the absorption at the violet end of the spectrum, and the spectrum consists 

 of a simple band of red, yellow, and green light. In solutions of intermediate 

 strength the two bands are connected by a clouding interrupted by brighter streaks, 

 while the more refrangible band is dark just about the region of F, and has its 

 main darkest mass separated from this dark narrow streak at F by a lighter 

 interval. 



