176 J . E. DuerpEn—Jamaican Actiniaria : 
though a slight disparity occurs in that forty-eight rows occur, while there are 
twenty-five pairs of mesenteries, forming, of course, fifty mesenterial chambers. 
The disc overhangs the column a little, and can be almost completely retracted. 
The base presents a very delicate opaque whiteness, and nearly the whole 
superficial area of the column shows a similar opacity, particularly evident in 
the upper region; clear and transparent areas may, however, remain in places, 
as at the verrucee. In the more distal region some of the ridges may be a delicate 
transparent brown. The colours of the knobs of the tentacles are variable, and 
not arranged according to any definite pattern. They are mostly opaque white, 
with various mottled colours on a clear transparent ground ; spots of yellow, brown, 
pink, red, and white are irregularly mingled. The marginal tentacles are more 
spotted with opaque white than are those more internal. Preserved in formol 
the specimen changed its colour as a whole to a dark brown. 
The column may extend to as much as 15 em. (6 inches) in height, and is 
about 5 cm. in diameter. 
Anatomy AND Hisrouoey. 
The ectoderm of the base is an exceptionally deep layer. Large numbers of 
long, unicellular glands occur of about the same diameter throughout, and 
contain finely granular matter. 
The mesogloeea is narrower than the outer layer, and is slightly fibrous in 
character; numbers of small cells are included within it. Internally it is finely 
plaited for the support of the endodermal muscle, which is here feebly developed. 
The endoderm is the narrowest of the three layers, and presents irregular 
internal limitations, and many granular gland cells. 
The column-wall is much and deeply folded, and of moderate thickness in 
each of its three layers. Peripherally the ectoderm appears somewhat dense, 
owing to the great abundance of unicellular glands with finely granular contents ; 
the cells extend from the inner limits of the layer, but become more swollen 
towards the outer surface. Though the polyp was nearly transparent when alive, 
the column-wall changed to an opaque dark brown on preservation in formalin, 
and the contents of the ectodermal cells appear yellowish brown on microscopic 
examination. The nuclei of the ectodermal supporting cells are mostly 
ageregated within a middle zone, and a slight ectodermal musculature is 
developed. 
The fibrous nature of the mesogleea is more obvious in the column than at the 
base, and the layer is very irregular in its outline, giving rise to numerous, deep 
folds on both its outer and inner aspects. On its endodermal border it forms, in 
addition, long, narrow, branching processes for the support of the strong, 
