380 Verrlll, JVotes on liadiata. 



peduncle and lower surface, but on the upper side arranged along the 

 edges of the polypiferous radiating lines, and especially concentrated 

 about the five (rarely six or seven) white points that surround the 

 closed polyps. The polyps are arranged somewhat in quincunx, in 

 lines that radiate from the attachment of the peduncle, and curve out- 

 ward on the sides to the lobes. The tentacles are narrow and taper- 

 ing, "04 to "06 long, bearing, especially in young specimens, well marked 

 pinnte at the tip and edges, which in old ones often become reduced 

 to a mere fringe." 



In alcohol the usual color is deep rich purple, due to the color of 

 the spicula, with the tip of the peduncle light yellowish ; but some 

 specimens are light, reddish purple, and one is pure white, due per- 

 haps to disease or injury, for it has become deformed. The polyps, 

 when expanded, usually show the eight white lobes around the mouth, 

 and the brown band below the tentacles. 



The spicula are all slendei- and irregularly prismatic in form, some- 

 times bent, a little thickened in the middle, tapering slightly to near 

 the ends, which are somewhat enlarged and bluntly truncated. They 

 vary considerably in size, those of the upper surface around the polyp- 

 cells and in the integument of the lower surface being the largest ; 

 many others are about half as long, and others not more than a fourth. 

 The largest spicula of the upper surface are about -810'""' long and 

 •064"'" thick ; some the larger ones from the lower surface are -544""" 

 long by -056'"'" thick, and •608'"™ long by -048'"'" ; with these are 

 many small ones about •350"'"' by •048""". Some of the larger spicula 

 from the white specimen are •640"'"' long by -004'"'" thick, and the 

 smaller ones •240°"" by •024""". The color of the spicula in the darker 

 specimens is deep amethystine purple ; in the lighter specimens, light 

 purple or silvery white. The spicula all reflect light in a peculiar 

 manner, which gives them a silvery lustre. They do not appear to 

 have such well marked triangular sections as those of " M. ameri- 

 cana^'' figured by Dr. Kolliker,* the angles being less prominent, 

 without reentrant angles between them. In many cases the section 

 is nearly round, or quadrangular with rounded corners, but to- 

 ward the ends of the spiculum, usually triangular with rounded 

 angles. 



When contracted in alcohol, one of the largest specimens measures 

 3^75 inches in breadth ; 3^30 long, from posterior lobes to front ; 2*20 

 from sinus to front; •SS in thickness; diameter of polyp-cells •OG. 

 When living, some specimens were more than 6 inches in breadth. 



* Icones Histiologica^, ii, Taf. xix, fig. 16. 



