Boone, Coelenterata, Cruises of "Eagle" and "Ara," 1921-28 57 



Material examined : Two large specimens from Nassau, Bahamas, 

 collected by the "Ara." 



Color: Variable. Light purple or purplish red, light yellow or 

 straw color, more rarely a white specimen is found. 



Discussion: Well-grown specimens of this sea-plume attain a 

 height of three and one-half to five and one-half feet, with a strong 

 elastic central stem and a great many long, slender, flexible, pinnate 

 branches, which are usually pendulous in the form of a loose plume. 

 Not infrequently large specimens consist of several such plumes, aris- 

 ing from a common base. The axis in the central trunk and main 



Test fig. 2. — Pterogorgia acerosa typica Bielschowsky, spicules greatly enlarged. 



branches is large, black, tough, horn-like, frequently much flattened 

 while in the terminal branchlets it becomes capillary or setiform, 

 translucent amber color. The spicules, which are the final diagnostic 

 character of the species, are embedded in the coenchyma and have 

 the shape shown in the figure. 



References: Gorgonia acerosa Pallas, Elench. Zooph, p. 172, 1766, 

 (with early synonymy). 



Pterogorgia acerosa forma typica Bielschowsky, Eva, Zool. Suppl. 

 16, Heft. I, p. 209, fig. 32, 1929, (with detailed diagnosis and 

 full synonymy). 



Order: Pennatulacea. 



Family: PENNATULIDAE. 



Genus: PTILOSARCUS Gray. 

 Ptilosarcus gurneyi (Gray). 



Plate 19. 



Type: Gray's type was from Monterey, California, and is depos- 

 ited in the British Museum. 



