MONOGRAPH OF THE EXISTING CBINOIDS. 747 



PIGMENT. 



While on the Challenger in the East Indian region Prof. H. N. Moseley investi- 

 gated the coloring matter of a number of comatulids and several pentacrinites. 

 His facilities were necessarily limited, but he secured some very interestiflg results 

 and was the first to demonstrate antedonin and pentacrinin. The value of his 

 work was unfortunately somewhat lessened by the absence of definite identifications 

 of the species he studied. 



Some years later Krukeuberg, in the course of his investigations at Trieste 

 into the coloring matter of various marine invertebrates, made a detailed study of 

 that of Antedon adi^iatica; and in 1890 Dr. C. A. MacMunn published the results 

 of numerous careful observations on such comatulid pigments as he was able to 

 secure, including that of Antedon bifida. 



From spectroscopic observations made during the voyage of the Challenger 

 Professor Moseley determined the existence of three different pigments in the 

 recent crinoids which he called purple pentacrinin, red pentacrinin, and antedonin. 



Purple petitaerinin.— Spectroscopic observations were made on the pigment of 

 the species listed below from the localities given : 



Off the Kermadec Islands, 630 and 650 fathoms: Hypaloci-inus naresianus, 

 Metacrinus nodosus, Metacrinus wyvillii. 



Off the Kei Islands, 126 fathoms : Metacrinus angulatus, Metacrinus cingvlatus. 

 fMetac7'inus murrayi, Metacrinus nobilis, Metacrinus tuberosus. 



Off Cebu, Philippines, 100 fathoms.* 



Between Panglao and Siquijor, Philippines, 375 fathoms; fEndoaiocrinus 

 alteniiciiviis, FHi/palocrinu^ naresianus, f Metacrinus nvurrayi} 



Off the Meangis Islands, 500 fathoms: Endoxocnnus alternicirrus, Hypalo- 

 crinus naresianus, Metacrinus costatus, Metacrinus mvseleyi, ? Metacrinus muiTayi, 

 Metacrinus variaiis, MetacHnv^ wyvillii. 



Professor Moseley found that the majority of the specimens yielded a coloring 

 matter which is extremely well defined by characteristic absorption spectra, and 

 which he called pentacrinin. 



When fresh the coloring matter is freely soluble in slightly acidified alcohol, 

 and gives a solution which is of an intense pink color when viewed by transmitted 

 light. 



The solution when moderately intense gives a spectrum consisting of three 

 bands. One of these, intensely black with sharply defined margins, covers the D 

 line, extending for a very short distance beyond the more refrangible side of that 

 line, and for a greater distance on its other side toward the red, as was observed 

 by viewing the spectrum with the bright sodium line in the field ; the second, situated 

 between D and E, is most intense on its least refrangible border, and shades off to- 

 ward the violet; the third band is a broad dim one stretching from l> to F. Very 

 little of the red end of the spectrum is cut off. The whole of the violet is absorbed. 



» In the Challenger report P. H. Carpenter does not mention the station off Cebu, and he questions the 

 correctness of the locality of all three species said to have been obtained off Panglao and SlqulJor. Some or 

 all of them may have come from off Obu. as none of the specimens hud definite locality labels when they 

 reached Carpenter's hands. 



