268 Papers from the Department of Marine Biology. 



Metalonome brunnea n. sp. 



Length of largest specimen, including gills, 30 mm. Length of gills, 10 mm. 

 Diameter of thorax, 3 mm. 



There are about 13 gills on a side, with relatively long pinnules, which have 

 a wavy outline, giving the whole gill a feathery appearance. The antennse 

 are short, broad at the base, with a very acute tip. The basal membrane of 

 the gills extends for only a short distance up the plumule, and in alcoholic 

 specimens this basal portion is a very dark brown, the color lightening very 

 gradually toward the colorless apex. 



Ends of collar widely separated on the dorsal surface, the dorso-lateral 

 portions rather low, the edges not reflexed (plate 3, fig. 24). Ventral to the 

 ventro-lateral notch the collar is produced on either side into a prominent 

 pointed lobe (fig. 25), whose length is more than twice the width of collar. 

 These lobes are in contact along the median line and cover a large part of the 

 bases of the gills. Dorsal to them, between the bases of the gills, is a pair of 

 lip-like folds, whose outer edges are in contact with and possibly are a pro- 

 longation of the ventral edges of the collar. 



There are 12 thoracic seta-bearing somites. The first seta tuft is near the 

 dorsal end of the collar, and there is no corresponding torus, while on the second 

 and later seta-bearing somites there is a ventral torus. The torus becomes 

 dorsal on the thirteenth setigerous somite. Ventral shields inconspicuous and 

 divided longitudinally throughout the abdominal region by a narrow line. 



The setae of the collar fascicle are long, the terminal portion expanded 

 laterally into a wing which is densely striated on its surface (plate 3, fig. 26, 

 from a profile view). The thoracic setae are in bundles, those of one side of 

 each bundle being similar in form to the collar setae, those on the other side 

 having a terminal expansion ovoid when seen in face; between these two is 

 a series graduating in form from one to the other; all have dense striations over 

 the broadened surface. The uncini have a large tooth and a crest of 5 or 6 

 rows of smaller teeth (plate 3, fig. 27). 



The tube is of thin white parchment covered at the end with fine white mud. 



Type and cotypes in the American Museum of Natural History. 



The specimens were collected at Nassau, British West Indies, by Whitheld. 



I was unable to discover any pennoned seta3 in the thorax of these forms, 

 and consequently have included them in the genus Metalonome as defined by 

 Bush (1905, p. 287). 



LITERATURE. 



AUGENER, H. 1906. Westindische Polychaeten. Bull. Mus. Comparative Zoology, 



Cambridge, vol. 43, No. 4. 

 BUSH, KATHERINE J. 1904. Tubicolous Annelids of the Tribes Sabellides and Serpulides 



from the Pacific Ocean. Harriman Alaska Expedition, vol. 12. 

 EHLERS, E. 1887. Florida Anneliden. Memoirs Mus. Comparative Zoology, Cambridge, 



vol. 15. 

 TREADWELL, A. L. 1911. Polychaetous Annelids from the Dry Tortugas. Florida. Bull. 



Amer. Mus. Nat. Hist., vol. 30. 

 WEBSTER, H. E. 1884. Annelids from Bermuda collected by G. Brown Goode. Bull. 



U. S. Nat. Mus. No. 25. 



