126 Natural History Bulletin. 



The Basal substance offers no peculiar characteristics. It 

 is relatively greater in amount than in PlexatireUa. The stel- 

 late mesodermal cells can not certainly be distinguished, and 

 their function as the point of origin of spicules, is proba- 

 bly taken by some of the quadrate cells, so thickly distributed 

 throughout the mesoderm. Basal substance is always found 

 between the primary water-vascular canals and the axis 

 cylinder. 



Spicules rather small and less numerous than in Briaretim 

 asbestiniim and Plexaurella dichotovia. They present in a strik- 

 ing degree the features which Kent regards as characteristic 

 of the genus Muricea.'' The peculiarity referred to is shown 

 in figs. 12, 13, 16, 17, PL III, where the long blunt spines are 

 seen to be aggregated on one side of the spicule and often 

 are confined to one end. The spines appear io be tubercles 

 greatly elongated with their long axes parallel and implanted 

 on the surface of the spicule so as to form a more or less 

 acute angle with its long axis. The spines seem to lean 

 toward the end of the spicule about which they are clustered. 



While the above may be said to be the characteristic form 

 of spicule for this species, a number of others may be found. 

 Many, for instance, are of the fusiform tuberculate (fig. 14), 

 fusiform echinate (figs. 10, 11), or arcuate tuberculate (fig. 19) 

 types. In some cases the spicules appear to be quadri-partite 

 (fig. 18) as in PlexatireUa. The lack of symmetry is a pecu- 

 liarity shared only by Phipidigorgia jlahelhim among the 

 species examined, and the long spines were found nowhere 

 else and therefore seem characteristic. 



In color these spicules are a deep purple-red sometimes 

 varying to pink. 



In that part of the coenenchyma immediately surrounding 

 the axis cylinder, the spicules are placed with their long axes 



I " The dominant form of spicula in this genus is coarse echinate unsym- 

 metrical fusiform, having spines or tubercles developed to a much greater ex- 

 tent on one side than on the other." Monthly Microscopical Journal, Feb. i, 

 1870, p. 84, and Plate XLI. 



