Dixon— On Sagartia venusta and Sagartia nivea. 125 



intermediate tint between these shades and the bright orange of 

 8. venusta. The absence of any intermediate condition is especially 

 noteworthy, when we consider that both forms, in many places, 

 grow together in profusion. 



In addition to the colour, the dimensions of the two forms 

 will help us in distinguishing them. The height of 8. venusta is 

 greater than that of 8. nivea, considered relatively to the diameters 

 of their columns respectively. Moreover, in 8. venusta the disk is 

 more inclined to be undulate in its outline, and more prone to 

 overspread the column than it is in 8. nivea. From this it follows, 

 that when the animal is only partially expanded the disk is more 

 concave and cup-shaped in 8. venusta than in 8. nivea, under 

 similar conditions. 



Dr. Andres' treatment of these forms is indeed remarkable ; 

 he keeps the species miniata apart, giving it to the genus Heliactis ; 

 on the other hand, he groups S. nivea, 8. venusta, 8. rosea, and 

 8. aurora (Gosse) together as Heliactis venusta, assigning as one 

 of his reasons for so doing the difficulty of finding specific points 

 whereby to keep them separate. Now, on this ground, I could 

 understand either all four forms, 8. miniata, 8. rosea, 8. nivea, and 

 8. venusta (the true place of S. aurora we shall presently see) being 

 placed together, or 8. miniata and 8. rosea being made to con- 

 stitute one species, for they undoubtedly have close affinities 

 (Gosse, Actin. Brit., pp. 43 and 50), while 8. nivea and S. venusta 

 were relegated to another ; but as S. rosea has far less in common 

 with 8. nivea and 8. venusta than 8. miniata has, it certainly should 

 not be placed with them, while 8. miniata is kept distinct. Dr. 

 Andres assigns as his second reason for so grouping these forms 

 the statement made by Mr. George Henry Lewes (Seaside 

 Studies, p. 142), that he saw 8. venusta change into S. aurora. 

 Let us see what are the circumstances on which this rather 

 astounding statement is based. 



In the year 1854 Gosse published a Paper (Ann. and Mag. 

 of Natural History, series 2, vol. xiv., page 281) describing 

 three new species of Actinia, with two of which only we are 

 now concerned. They are Actinia aurora, which he also named 

 " the orange-tentacled anemone," and Actinia venusta, which he 

 called "the orange- disked anemone." Gosse subsequently saw 

 that Actinia aurora was only a variety of Sagartia troglodytes, and 



