Nos. 622-623] SHORTER ARTICLES AND DISCUSSION 553 



matter — in descriptive lists somewhat confusing— a rather in- 

 teresting point, which it is the purpose of this note to elucidate. 



Mellita, adult, is at Bermuda undoubtedly brown ; large speci- 

 mens (9.0-11.5 cm. in transverse diameter, usually 9.5 cm.), 

 which I have from time to time collected by dredging upon 

 grass-free bottoms of fine sand or mud at Flatt's Inlet, Spanish 

 Point, Two Rock Passage, and other localities, are uniformly 

 brown upon both aboral and oral surfaces, although the different 

 individuals vary somewhat as to shade. Their general hue 

 harmonizes well with that of the substratum. It is improbable 

 that light has had a direct effect in producing pigmentation, 

 since the oral surface, never turned toward the light, is at least 

 as densely pigmented as the aboral one and is frequently (in 

 larger specimens) darker. Young individuals in an active, 

 healthy state were gotten in association with adults during the 

 autumn months. Up to 5 em. diameter, in one case 8 cm., they 

 were found, with one exception in about 30, to exhibit no brown- 

 ish coloration whatever ; they were, on the contrary, pure white, 

 and translucent, the yellowish stomach being easily made out 

 through the test. These individuals were usually 3.5 to 4.0 cm. 

 in transverse diameter. The one exceptional specimen, 2 cm. 

 in diameter, was unusual because it was of a light coffee-brown 

 shade. 



When placed in alcohol, or in fresh water, these young ivhite 

 Mellitas became bright green ; in sunlight the green on alcoholic 

 specimens quickly disappears. Clark (1901, p. 254) notes that 

 some young specimens of M. pentapora examined by him were 

 green [in alcohol?]. 



When kept in aquaria for several days the small white "sea- 

 plates" developed, in most cases, local indications of green pig- 

 ment, although the animals were still quite active. This was 

 also true of the large brown individuals. It was noticed that 

 in cases where a large brown Mellita had been damaged by the 

 cutting edge of the dredge, a green coloration was present along 

 the wound when the haul was brought to the surface. Other 

 specimens, apparently uninjured, sometimes developed an olive- 

 green color on the oral surface within half an hour after being 

 transferred from the dredge to a tub of sea water. 



Thus the green coloration of Mellita is associated with a con- 

 dition of injury or death. It is possible that the green material 

 may have no connection with the substance responsible for the 

 general brown integumentary coloration of adults. 



