The Actiniae of the Plate ('ollection. 273 



at the tips. Tliey are decidedly entacmaeous, the inner ones being- 

 at least four times the length of the onter. In the expanded indi- 

 viduals the mouth is widely open and the stomatodaeum is seen to 

 be strong-ly ridged, the ridges being twenty-fonr in number. Two 

 distinct siphonoglyphs occur. 



The larg-est specimen. which was contracted, measured 4.3 cm 

 in heig'ht and had a diameter at the snmniit of 2.5 cm. The larg'est 

 of the expanded individnals measured 2.3 cm in heig-ht. with a 

 diameter at the base of 1.7 cm, at the middle of 1.1 cm and at 

 the margin of 2 cm. 



The column in all the specimens is distinctly brown, the color 

 deepening- to a chesnut brown on the tubercles of the column, in 

 the tentacles and on the stomatodaeal ridges when these are exposed. 

 This coloration, however, is probably the result of the tixation of 

 tlie specimens in a chrom-osmic Solution and the tentacles and 

 stomatodaeum in contracted specimens are colorless. A label which 

 accompanies specimens No. 574 states that the bod}' and tentacles 

 were rose-colored. 



Structure. The mesogioea of the column wall is very mucli 

 thicker than the ectoderm and has a finely tibrillar structure. The 

 circular nuisculature is well developed and the strong- mesog'loeal 

 sphincter (Fig-. 60) is finely reticular in structure, without any 

 layering", and is of an elong-ate triangnlar form, having a width in 

 the largest individual of about 5 mm. In the uppermost part of 

 the wall, above the tubercles, it occupies the entire thickness of the 

 mesogioea and in this portion the meshes are elongated ; lower down 

 it is separated from the ectodeim by a layer of ordinary mesogioea 

 which increases in size as it is traced dowuward, the sphincter ]ymg 

 throughout its entire extent in dose proximity to the endoderm 

 The meshes throughout all the lower portions of the muscle are 

 circular. 



The longitudinal muscles of the tentacles and the radial nuis- 

 culature of the diso are rather weak and show no signs of being 

 included in the mesogioea. 



The mesenteries are arranged hexamerously in five cycles, of 

 which the tirst three are perfect, the third, however, separating from 

 the stomatodaeum some distance above its lo\ver edge. There are 

 two pairs of directives. The mesogioea of the mesenteries is rather 

 thick, and toward the column wall is specially so (Fig. 61), a marked 

 fold arising from the inner edge of this basal thickening being the 



