THE OPELET. 161 



Tentacles. About one hundred and eighty, arranged in four rows; of 

 which the first, second, and third contain thirty-six each, the fourth 

 seventy-two. These numbers are, however, only approximative; for the 

 crowded condition of the tentacles, the irregularity of their serial arrange- 

 ment, and the ever-varying distension of the disk, make it almost impos- 

 sible to count, much less accurately to distribute them into rows. They 

 are sub-equal in length ; but what difference there is, is a diminution out- 

 wards. All are very long ; those of the first row sometimes upwards of 

 four inches in length, and more than doubling the diameter of the disk : 

 they are slender, and taper uniformly to the tip, which is obtuse and as if 

 truncate, or sometimes slightly enlarged ; very lax and flexuous, they are 

 almost always thrown about in irregular, snaky curves, intertwisting in all 

 directions. Their entire surface is very adhesive. 



Mouth. Seated on an elevation, which more commonly takes a cylin.- 

 drical than a conical form ; sometimes large and tumid, at others small : 

 lip rounded. 



Colour. 



Column. Pale wood-brown, umber-brown, purplish-brown, or flesh- 

 colour, marked with numerous narrow bands alternately paler and deeper, 

 which correspond to the furrows ; sometimes the lighter bands are dull 

 light lilac, with darker edges. 



Disk. Dark bistre-brown, or umber-brown; the gonidial radii often a 

 lighter shade of the same colour. 



Tentacles. Light pea-green or emerald-green, opaque, with a rich, 

 satiny lustre; the extreme tips, for about one-fourth of an inch, rich 

 lilac-crimson ; the green gradually blending into the lilac, and the latter 

 hue increasing in brilliancy to the extremity. A faint whitish line usually 

 runs along the back of each tentacle throughout its length. 



Mouth. Lip agreeing with the disk ; throat ash-brown. 



Size. 



Large specimens are sometimes seen covering an area of six inches in 

 diameter, with their tentacles four inches long ; the disk two inches, and 

 the column the same, in diameter. 



Locality. 



The western and southern coasts of Europe generally. Shallow pools 

 between tide-marks, and littoral rocks. 



Varieties. 



a. Smaragdina. The state described above, with rosy-tipped green 

 tentacles. 



