the Actiniarian Family Aliciidoe. 13 



the exception of an occasional isolatetl cell, is homogeneous 

 in structure. It is plaited a little on both the ectodermal 

 and cndodermal borders tor the support of the musculature. 

 Tiie endoderm-cells are often very long in section, the layer 

 having irregular internal boundaries. ZooxanthelliE are 

 present. 



Disk. — The ectoderm is thick and ciliated ; elonjrated 

 nematocysts are present ; the mesogloea and endodcrm are 

 the same as in the tentacles. An cndodermal musculature is 

 seen. 



(Esophagus. — The oesophageal walls are much folded, but 

 there is no indication of any sj^ecial groove; the ectoderm and 

 endoderm are much thicker than the mesogloea. 



1'he ectoderm is richly ciliated, and, in addition to the 

 outer zone of narrow nematocysts, contains abundant irregu- 

 larly distributed large stinging-cysts. The nuclei are arranged 

 in a broad zone ; a very weak ectodermal muscle is seen in 

 transverse sections, and a similar endodermal muscle in longi- 

 tudinal sections. 



Mesenteries. — In the region of the oesophagus twelve pairs 

 of perfect mesenteries, including two pairs of directives, are 

 present, and pairs of very short imperfect mesenteries alternate. 

 They are broad towards the column-wall, but narrow towards 

 the oesophagus ; zooxanthellai are sparingly present in the 

 endoderm. The longitudinal retractor muscles are well 

 developed for some distance on one side and the mesogloea is 

 thrown into supporting folds. Below the oesophagus the 

 mesenteries branch, the endoderm becoming much thickened ; 

 each division is terminated by a rounded mesenterial filament 

 bearing abundant nematocysts, and continuous with the 

 ectoderm of the oesophagus. 



Gonads. — No reproductive cells were present in any of the 

 examples sectionized. 



The distinctions between these two species are, in several 

 respects, those of degree rather than of kind. Practically all 

 the characters strongly marked in the first appear to be 

 present in the second, but developed to a less extent. The 

 average dimensions of the Antillean representative are two or 

 three times those of the Mediterranean specimens received. 

 Of a score of specimens received from Naples, preserved in 

 4 per cent, formalin, none exceeded 0*4 centim. in diameter 

 across the base, while an average diameter of the Jamaican 

 forms is 1*3 centim. The colour distinctions may be of some 

 moment. The column in Andres's species has yellowish- 

 brown-ochre bands ; these are never met with in the new 



