164 DONALD WALTON DAVIS 



these extreme dimensions approached simultaneously in the 

 same individual. In the majority of specimens the more ex- 

 treme measurement does not exceed half the stated maximum. 



The ground color of the column is olive-green. A variable 

 number of orange or yellow stripes extend along the whole 

 length of the column from the oral disc to the base. Less con- 

 spicuous vertical lines along the column, darker than the ground 

 color as seen by transmitted light, mark the attachment of the 

 mesenteries. 



In oral view the siphonoglyphs, commonly two, may be 

 distinguished with the aid of a hand lens. Except in very small 

 specimens or in early stages of regeneration, each siphonoglyph 

 is clearly marked by a chalk-white bar which extends from the 

 siphonoglyph radially across the disc. The white bars appear 

 with approximately normal prominence in the photographs 

 shown as figures 1 and 2. 



In its internal arrangements this anemone follows the general 

 Hexactinian plan, yet with great variation in detail. The 

 number of siphonoglyphs and associated pairs of directive mesen- 

 teries is conmionly two, but may be one, three, or rarely four 

 (tables 11 and 13). In one specimen five pairs of directive 

 mesenteries were noted. The number of pairs of complete non- 

 directive mesenteries varies approximately from four to eleven; 

 although specimens may frequently be found, at an early stage 

 of regeneration when the new mesenteries have not become 

 established, with less than four pairs of non-directives in evidence. 



The form resulting from ontogenetic development has not 

 been determined with certainty, but is probably (p. 218 ff.) a 

 regular hexameric one with two siphonoglyphs, two pairs of 

 directive mesenteries and four pairs of non-directives (fig. 26). 

 In the animals studies, one, two, three, or even four (fig. 25) 

 cycles of incomplete mesenteries are present. These are quite 

 regular in number and arrangement in an area formed at one 

 time, but vary greatly between newer and older regions of a 

 regenerated animal. 



I shall use the terms ' endocoel' and ' exocoel' in their accepted 

 significance, the former indicating a space between the members 



