166 CAROTINOIDS AND RELATED PIGMENTS 



animals have been described by many zoologists. In general the 

 colors of the cchinodcrms resemble very closely those of the Crustacea. 

 From the standpoint of the pigments proper the same red and yellow 

 carotinoid-like pigments found in Crustacea appear to be the cause 

 of like colorations, and, in addition, blue and green lipochromogens 

 are also encountered. From observations cited in Miss Newbigin's 

 Monograph (1898) the blue and green colors are more common in 

 species found in shallow water than in the deep-sea forms, where red 

 colors predominate. 



Merejowsky (1881) first called attention to the properties, later 

 ascribed to lipochromes, of the red pigment in echinoderms, and cited 

 twenty or more species, representing the various orders, in which it 

 occurred. He used the name zoonerythrine for the pigment, and later 

 (1883) reaffirmed his previous observations, especially the presence 

 of the pigment in the sea cucumber Holothuria tubulosa, which had 

 been denied by Krukenberg. The observations on the chromolipoids 

 in the Holothuroids have, in fact, been contradictory. Krukenberg 

 (1882J) called the skin pigment of Holothuria Poli uranidine, but later 

 (1882k) stated that "rhodophane" is present in an especially pure 

 condition in the ovaries and blood vessels of this species, while Mac- 

 Munn (1890) found no lipochromes in this species, but reported a 

 'rhodophane-like lipochrome" in the blood and "liver" of other species, 

 namely Holothuria nigra and H. Ocnius brunneus. The single absorp- 

 tion band of this pigment in ether was placed by MacMunn at 507- 

 471 [41. 



It is evident from the observations of Krukenberg (1882k) and 

 MacMunn (1890) that in the star-fishes, at least, chromolipoids show- 

 ing two-banded spectra and more nearly resembling true carotinoids 

 predominate over the red pigment showing only one band. Kruken- 

 berg described such a pigment in the skin and "liver" of the species 

 Astrospecten aurantiacus and Asteracanthion glacialis, under the name 

 orangin (on account of its color), and MacMunn described similar 

 carotinoid-like pigments in the orange-colored ovaries of Astcrina 

 gibbosa. These pigments may be xanthophyll, judging from the ab- 

 sorption spectra described by Krukenberg. It is evident, however, 

 that carotin may be the cause of the red, two-banded pigment found 

 by MacMunn in the integument of Goniaster equestris, Cribella ocu- 

 lata and Solaster papposa. The red ovaries of the Cribella species 

 contain the same pigment. 



Of the other forms of echinoderms, no special examinations of pig- 



