750 PROCEEDINGS OF THE AMERICAN ACADEMY. 



same structure as those of the polyp wall. Sense cells, like those in 

 the body wall and tentacles, are found in the batteries and increase 

 in number with the increase in the number of cysts in the batteries. 



Some of the ectoderm cells of the coenosarc between the polyps 

 contain a prominent, highly refractive, homogenous fiber (Plate 3, 

 Figs. 24, 2(),fbr. sst.), beginning near the nucleus and extending to the 

 base of the cell, which is implanted in the mesogloea. The nature of 

 these fibers is not perfectly certain, but it is probable that they are 

 the same as the "Stiitzfasern" described by K. C. Schneider (.:02, 

 p. 622) for Anemonia; however, I have never seen evidence of their 

 fibrilation, such as Schneider has shown to exist in the case of t^'pical 

 "Stiitzzellen." Figure 26 shows the distribution of these Stutz- 

 fasern in the coenenchyma and their relation to the grooves which 

 occur in these regions. 



The ectoderm of the disk is, in its content and cell structure, like 

 that of the oral face of the tentacle. When the disk is fully expanded, 

 the stomodaeal epithelium reaches over on to the disk. The siphono- 

 glyph and the dorso-lateral regions of the stomodaeum are both 

 characterized by extremely long columnar ciliated cells. The siphono- 

 glyph (Plate 3, Fig. 32) has neither gland cells nor nematocysts, both 

 of which are abundant in the other regions of the stomodaeum (Figs. 

 30, 31). The columnar cells of the siphonoglyph are long and of small 

 caliber; each has a single strong cilium, or flagellum, which is longer 

 than the cell. The cytoplasm is finely and rather densely granular, 

 and each oval or elongated nucleus has one or two prominent nucleoli 

 and a small number of chromatin granules. The nuclei occupy dif- 

 ferent levels in adjacent cells and are so situated that collectively they 

 form a definite layer. Four la^^ers, then, are recognizable in the ecto- 

 derm of the siphonoglyph (Fig. 32): (1) subnuclear, composed of 

 the bases of the columnar cells, between which may be found occasional 

 nutrition cells {cl. nut.) and ganglion cells, (2) the nuclear la3'er, (3) the 

 la^'er between the nuclei and the basal granules of the cilia, (4) the 

 cilia layer, a wide border characterized by the long and prominent 

 basal granules. No ectodermal muscle cells are found in this region. 



In the dorso-lateral portion of the stomodaeum (Plate 3, Figs. 30, 

 31) four types of cells occur abundantly, supporting cells (cl. sst.), 

 nnicus cells (cl. muc), granular gland cells {cl. gni.), and the small 

 nematocyst cells {cl. nni'cys.'). The same four layers as in the siphono- 

 glyph are found, but the nuclear zone is much wider, and the cell 

 bases do not always terminate so sharply against the mesogloea. 

 The cilia are short. The supporting cells {cl. sst. and Fig. 39, Plate 4) 



