Yerrill, Notes on Radiata. 361 



but agreeing in color, form of cells, etc. Intermediate specimens are 

 frequent. The cells are sometimes prominent on the main branches, 

 near the base ; but on the terminal branches are but little prominent, 

 opening upward. They are usually closely crowded on all sides. 

 Color lemon-yellow. Height 4 to 6 inches ; diameter of branches, 

 •10 to "24 of an inch, usually about •\h. 



Spicula mostly large, lemon-yellow and yellowish white, with a few 

 very small, deep purple ones. The forms are very diverse ; the largest 

 are mostly stout fusiform, often crooked, not very acute " spindles," 

 thickly covered with rough papillfe ; other fusiform spicula are less 

 than half as long, slender, acute at the ends, with fewer separated 

 papillfe. The purple ones are still smaller, slender, acute spindles, 

 with prominent papillfe. Club-shaped spicula are numerous, of vari- 

 ous sizes, the large end very thick and covered with prominent shai'p 

 papillje ; others have such papillae only on one side. Various interme- 

 diate forms of spicula are abundant. 



Very abundant below low-tide on the borders of the coral reefs of the Abrolhos 

 and at Porto Seguro, where it also occurs on the stone reef, and in shallow water 

 along shore. It is abundant at Bahia. Occasionally found in the larger tide-pools — 

 c. F. H. 



PI xaurella dichotoma Koiiiker. 



Icones Histiolog., p. 138, Taf xviii, f 11, 1866. 

 Gorgonia dichotoma Esper, Tab. xiv. 

 Plexaura dichotoma Dana, Zooph., p. 669. 



Plate IV, figures 5, 5% 5^ 



Several specimens of a Plexaurella, closely allied to this, if not 

 identical, were collected at the Abrolhos, by Mr. Hartt. These are 

 about a foot in height, consisting of 4 to 8 large, round, elongated 

 branches, which originate from near the base and seldom divide, of 

 nearly uniform diameter, about '5 inch throughout, except at the ends, 

 where they are often enlarged or capitate. Cells large, rather numer- 

 ous, often slightly raised, but usually flat, with a broad oval opening, 

 or with contracted narrow ones, which are linear and at various angles 

 to one another. All these variations may occur in one specimen. 



The spicula are of several forms, many having four stout branches, 

 forming thick, stout-armed crosses, agree well with Dr. Kolliker's fig- 

 ure ; others occur with three or even six branches ; but a large pro- 

 portion are short fusiform, with a naked band around the middle. 

 All are thickly covered with rough papillae, and have tapering, rather 

 blunt ends. Spicula of the typical P. dichotoma^ prepared and sent 

 to the author by Dr. Koiiiker, do not appreciably differ. 



