230 



branchial aperture is rounded, with six short cirrhi within ; the 

 anal is square. Dianrieter half an inch. 



It occurred on a sandy bottom, in six fathoms in Boston Bay ; 

 and also at low water on Bird Island. The tadpole-like young 

 were ejected in August, and were of a bright vermilion color, 

 which continued for a long time after their final detachment. 



M. ARENATA. Body somewhat compressed laterally. Test 

 thin, uniformly covered with coarse sand, which adheres very 

 strongly. Apertures small, on very short tubes, far removed 

 from each other. Length three fourths of an inch. 



It inhabits the region of Nantucket and Martha's Vineyard. 



GLANDULA, 11. g. 



Body globular, always free, and thickly coated with sand, 

 mud, or other extraneous substances. Apertures on tubes, the 

 branchial with four lobes, the anal square. Branchial sac with 

 few, distant plications. 



G. FIBROSA. Test thin, but very tough and leathery, covered 

 with numerous fibres resembling cotton, which serve as a frame- 

 work or attachment for the hard, thick coating of mud, in which 

 this species is always found incased. Thus a ball is formed of 

 about one inch in diameter, twice that of the body alone. The 

 tubes extend only to the surface of the ball. It is an exceedingly 

 tough, hard species, and when divested of its covering will bear 

 the weight of several pounds without bursting. 



Dredged in thirty-five fathoms on a muddy bottom, in the 

 Hake Bay, off Gr. Manan. 



G. MOLLIS. Body globular, but often considerably flattened, 

 soft, and flexible. Test very thin, transparent, and thickly 

 covered with loose sand. Diameter half an inch, usually less. 



Dredged abundantly on a sandy bottom in ten fathoms, off 

 Cheney's Head, Gr. Manan. 



CYNTHIA. 



C. viTTATA. Body oblong, somewhat arcuated, often laterally 

 compressed. Test thick, cartilaginous, opaque, white, or pale 

 yellowish, with large longitudinal wrinkles or furrows. Orifices 

 square, on short, conical tubes, which have a pair of dark red, 



