PELONAIA. 27 



third, contain the apertures. The two polygons are wheel-like, 

 being radiated with six spokes from a centre, which is the sessile 

 aperture. Proceeding from and perpendicular to each of the dark 

 lines arc bright straw-colored fibres, extending toward the cen- 

 tres of the polygons, but not reaching tliem. Length, half an 

 inch. 



Dredged in forty fathoms, on a muddy bottom, off Long Island, 

 Grand Manan. One specimen only was found, which was adher- 

 ing to a dead valve of Pecteii Mag-e/laiiicus. (^Stimpson.} 



Genus PELONAIA, Forbes and Goodsir. 18-40. 



Test cylindrical ; orifices terminal, four-cleft, on two small, ap- 

 proximated, papillose eminences ; mantle adherent to the test ; no 

 tentacles. Ovaries two, symmetrical. 



Tliis genus, in its cylindrical body and terminal orifices, resem- 

 bles Siphuncidus among the Echinoderms. They have relations 

 also witli the Annulosa in the transverse plaits of the respiratory- 

 sac, and in being bilateral. One of their most striking peculiari- 

 ties is the perfect union of the test and the mantle. The Pe- 

 lonaice live buried in mud, quite unattached to any other body, 

 and are extremely apathetic animals, presenting scarcely any aj> 

 pearance of motion. 



Pelonaia arenifera. 



Pdonaia arenifera, Stimpson, Proc. Bost. Soc. N. II. iv. 49 (1851) ; Check Lists, 2 (1860). 



The body is elongated, clavate, of a l)rownish color, and covered 

 with grains of sand ; tlie apertures are placed on two small, white, 

 mammilliform protuberances at the smaller extremity. It inhabits 

 deep water ; the specimens were obtained from eighteen fathoms, 

 about ten miles east of the Boston Lighthouse. (^Stimpson.^ 



