Tne Actiniae of the Plate Collection. 231 



sliaped form measured 2 cm in lieight and 1.8 cm in diameter at 

 about the middle of the column, while another individual, frora Tumbes, 

 measured 1.4 cm in height with a diameter of 1.5 cm at its broadest 

 part and of 0.8 cm at the base. One of the more elongated indi- 

 viduals measured 2 cm in height with a greatest diameter of 1.1 cm. 



None of the specimens showed any distinct coloration of the 

 column, although a brownish pigment occurs in the endoderm. The 

 tentacles were brownish, the color being due to endodermal pigment. 

 The stomatodaeum was longitudinally ridged and the siphonoglyphs 

 were well marked. The margin was indistinct but smooth and 

 separated by a slight fosse from the bases of the outermost tentacles. 



Structure. The mesogloea of the column wall is distinctly 

 fibrous in structure and is raised upon its ectodermal surface into 

 numerous ridges which produce the transverse wrinkles mentioned 

 above. Throughout the greater part of the column the ectoderm is 

 nearly as thick as the mesogloea, but toward the margin the latter 

 thickens distinctly. The endodermal circular musculature is but 

 feebly developed and a sphincter can hardly be said to exist, 

 although the muscle processes are a little more pronounced at the 

 Upper part of the column than elsewhere. 



The musculature of both tentacles and disc is feeble and is not 

 imbedded in the mesogloea. The stomatodaeum is longitudinally 

 ridged and possesses in all the specimens examined two well deve- 

 loped siphonogl^yphs. 



The mesenteries present several interesting features in their 

 arrangement. In sections passing through the middle of the column 

 there are twenty-four pairs of mesenteries visible, twelve pairs, in- 

 cluding the two pairs of directives, being provided with strong longi- 

 tudinal muscles, while the remaining pairs are small and destitute 

 of muscle pennons and mesenterial fllaments. In the upper part of 

 the column the twelve large pairs are perfect, but before the lower 

 edge of the stomatodaeum is reached six of them become separated 

 from it and as they are traced down the column they lose their 

 mesenterial fllaments and the muscle pennons diminish in size and 

 eventually disappear (Fig. 12), so that in the lower portion of 

 tlie column only six pairs of mesenteries with pennons and mesen- 

 terial fllaments occur. It will be observed that the number of mesen- 

 teries does not agree with that of the tentacles, of which there are 

 representatives of five and, in some cases, of six cycles. In sections 

 through the marginal region of the column it was possible to detect 



Zool. Jahrb., Supplement. Bd. VI. (Fauna Chilensis. Bd. III.) Heft 2. 16 



