REPORT ON THE HEXACTINL^ 37 



while in that by Dr. Calkins they agree more with the condition 

 in the preserved specimens. They are quite smooth and are ar- 

 ranged in about four cycles and are fairly numerous, though I 

 did not succeed in making an accurate enumeration of them- 

 The disk is smooth and somewhat concave and the peristome 

 slightly elevated. The lips are ridged and there are two rather 

 feebly marked gonidial grooves in the specimens examined. 



Color. — Dr. Calkins describes the individuals obtained by him 

 as being ''crystalline" in appearance with '* pink-tipped tenta- 

 cles." The drawing which accompanied his notes (Fig. 17) 

 shows the column, disk and bases of the tentacles to be faintly 

 greenish-yellow, the tips of the tentacles being the only brightly 

 colored portions of the animal. Mr. Agassiz's drawing, which 

 is undoubtedly of the same species, represents the column as 

 being of a bright green color, the disk of a dark olive green ; this 

 color extending upon the bases of the tentacles, being there suc- 

 ceeded by a yellow band, beyond which the tentacles are of a 

 bright pink. 



Size. — The preserved specimens sent me measured i. 0-1.5 

 cm. in height and about the same in diameter. Dr. Calkins 

 states that the largest individuals " when expanded, measured 

 fully three inches across the crown, but the average was much 

 less." 



Stnicture. — A longitudinal section of the column wall re- 

 sembles closely what I have described and figured for Cribrina 

 elegantissiina. The tubercles differ from those of Cribrina only 

 in the absence of a special development of endodermal muscles 

 at their summits and in the presence of a distinct though fine 

 band of nerve fibers in the basal portion of the modified ectoderm. 



The sphincter is situated upon the floor of the fosse, just in- 

 ternal to the acrorliagi. It is oval in section and is of the pe- 

 dunculate palmate variety (Fig. 22). The ectoderm of the 

 acrorhagi is abundantly supplied with nematocysts, whereby they 

 can readily be distinguished from tentacles in section. In these 

 latter the longitudinal musculature is not imbedded in the mes- 

 ogloea and resembles in appearance that of C. elegantissiina, as 

 does also the radiating musculature of the disk, though here the 



