POLYPS AND CORALS. 183 



PTILOSARCUS. 



This section of the genus Sarcoptilus Gray seems to be 

 sufficiently distinct from the original type of that group to 

 rank as a separate genus. 



The form is thick, club-shaped ; the pinnae numerous, 

 crowded, with thickened edges on which the polyps are 

 arranged in several rows, each cell surrounded by promi- 

 nent, spine-like spicula. The back of the body, except 

 along a narrow median space, as covered by two broad 

 bands of rudimentary polyps, appearing like crowded gran- 

 ulations. The basal portion is thick and bulbous, with two 

 large interior cavities, one of which extends along the an- 

 terior surface, communicating with the pinnae, the other 

 along the dorsal portion. 



The axis is long, fusiform, tapering to very slender points, 

 which are curved (in preserved specimens) into a loop at 

 each end. Connected with the lower part of the axis are 

 very strong thickened muscles, which pass obliquely up- 

 ward and outward to the wall-tissues, while higher up, a 

 little above the lowest pinna), other shorter ones are at- 

 tached, which pass obliquely downward to the wall. 



PTILOSARCUS GURNEYI. 



Nnrcoptihis (Ptilosarcus) G-urneyi J. E. Gray, Ann. and Mag. Nat. 

 Hist., Vol.5, p. 23, pi. Ill', f. 2, 1800; ? Pmnatula tenua Gabb. Proc. 

 Cal. Acad. Nat. Sciences, IE. page 106. 18G2. 



Basal portion about one half the whole length, thick, 

 bulbous, very muscular, the surface strongly sulcated in 

 contraction. Pinnas smooth on the sides, broad, rounded, 

 nearly semicircular with a broad base, the posterior edge 

 extending beyond the base as a rounded lobe : the edge is 

 thickened and covered by the polyps arranged in four rows, 

 each cell armed with two sharp spinules. Along the back 

 are two broad bands of very small papillae or granuliform, 

 rudimentary polyps. 



Length of a large alcoholic specimen, having fifty-two 

 pinnas on each side, 10 inches ; greatest breadth 2 ; length of 

 pinnae .80, breadth 1.50; length of naked base 4.75, diame- 

 ter 1.25. 



Puget Sound, Wash. Terr. Dr. C. B. Kennerly, Dr. G. 

 Suckley. (Coll. Smithsonian List.) 



