rhe Actiniae of the Plate Collection. 245 



Genus PycnantJiiis McMuerich 1893. 



Paractidae witli a thick coliimn wall, destitute of tubercles or 

 Verrucae, but with capitular ridg-es; margin tentaculate, not lobed; 

 tentacles slender and not bulbously enlarged at the base. 



9. Pycnanthiis lineolatus (Mc Murrich). 



Paradis lineolata McMuRRiCH, 1893. 

 ?Äctmia lineolata CoüTHOUY, 1846. 



Juan Fernandez. 30 fathoms. 1 specimen. 



The Single specimen of this species (Fig. 27) was strongly 

 contracted, the upper portion of the column being completely infolded 

 and the tentacles concealed. The base was adherent and the column 

 had the form of a low dome, its walls being perfectly smooth, except 

 for some irregulär circular furrows, due to contraction, and radial 

 ridges upon the summit which were probably the continuations of 

 the capitular ridges. 



The height of the column was about 2.5 cm, and its diameter 

 at its widest part 3.2 cm. In color it was probably uniformly 

 chocolate brown, the coloring matter being located in the ectoderm, 

 so that where this had been removed and the underlying mesogioea 

 exposed, white blotches occurred. 



Structure. The column ectoderm was very uniform in 

 structure, consisting of cells about 0.26 mm in height whose basal 

 portions were densely packed with pigment granules of a yellowish- 

 brown colour and so flne that they gave the appearance of an almost 

 homogeneous coloration. I could detect no gland cells and no 

 nematocysts in my preparations. The mesogioea was very thick, 

 measuring 3.0 — 3.5 mm in thickness, and contained numerous minute 

 cavities occupied by cells and lying in an almost homogeneous 

 ground substance. It is interesting to note that in the outermost 

 portions next the ectoderm, the contents of the cavities were colored 

 by the same pigment as occurred in the general ectoderm. In the 

 infolded portion of the column the mesogioea increased in thickness, 

 until at the junction with the disc it was almost twiec as thick as 

 it was lower down and its surface was raised into distinct longi- 

 tudinal ridges, giving it an appearance such as is seen in the cap- 

 itulum of certain PheUnnae. I could not determine the number or 

 arrangement of these capitular ridges without mutilating the Single 



