Dixon — On Sagartia vemista and Sagartia nivea. 117 



Disk — Flat, or very slightly concave ; the margin scarcely 

 undulate, and rarely expanded so as to overhang the column ; out- 

 line circular ; radii conspicuous, forty -eight in number, of which 

 twenty-four run from the mouth to the feet of the tentacles of the 

 first row ; and the remaining twenty-four, which alternate with 

 those just mentioned, are subdivided by the insertion of secondary 

 and tertiary radii, which run to the feet of the tentacles in the 

 second and third rows, respectively, but do not reach the mouth. 



Tentacles — In number, 192, set in four rows, of which the first 

 and second contain each twenty-four, the third forty-eight, and the 

 fourth, which is marginal, ninety-six. This would appear to be 

 the usual arrangement, though slight deviations are not infre- 

 quent. Those of the first row, when extended, are about as long 

 as the diameter of the disk, and are generally turned upwards and 

 outwards ; the tentacles in the other rows diminish gradually, and 

 are bent back further ; those in the outer row are frequently ex- 

 tended horizontally to the disk : they are small, and are sometimes 

 contracted to the condition of mere papilla), so as to form a fringe. 



Mouth — Generally swollen and gaping, frequently thrown into 

 lobes, sometimes raised on a cone, furnished with either one or two 

 oesophageal grooves ; lip tumid, and marked with ridges which 

 terminate the radii ; a pair of oesophageal tubercles mark the junc- 

 ture of the oesophageal groove with its corresponding radius, 

 specimens with two grooves having, of course, two such pairs of 

 tubercles ; throat ridged ; acontia emitted freely and copiously 

 through the cinclides and the mouth. 



Colour. 



Column — A very pale olive-drab to orange-brown ; slightly 

 varying in intensity, becoming paler towards the base, which is 

 often marked by longitudinal lines of white, which fade as they 

 ascend. The lines showing the insertion of the mesenteries are 

 conspicuous throughout ; suckers white. 



Disk — Opaque-white to greyish- olive, without markings other 

 than the radii, and pellucid spots, which in some cases may be 

 seen, when the animal is well expanded, at the foot of each of the 

 tentacles in the inner row. Occasionally a faint tinge of yellow 

 surrounds the mouth, and a shade of smoke-grey the tentacular 

 region. 



