492 . RADIATA. ASTERIAD^. Priapulus. 



Length about 6 inches, diameter half an inch ; the middle of the body is 

 nearly of equal thickness, divided into flat smooth rays, with scattered glan- 

 dular pores ; the anterior portion is enlarged, annulated, and longitudinally 

 striated ; mouth orbiciilar, marginated, the disc, within, armed with sharp 

 tricuspidate teeth ; the posterior part of the body is also enlarged, obscurely 

 annulated and rough, with glandular tubercles ; vent semilunar, with a late- 

 ral pore ; the branchiae proceed from the margin of the vent, in the form of an 

 elongated process, two or three inches long, tapering, and closely covered 

 with simple produced papillae ; from one edge of the branchiae a tendinous rib 

 arises, extending nearly to the mouth, — This genus has numerous relations 

 to the Holothuria, and a few also to the Annelides. One specimen occurred 

 to me in Zetland, in 1810, and two have recently been found by Dr Cold- 

 stream, at Leith. 



