INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 597 



through a large part of the length, narrowed slightly and gradually 

 toward the posterior end, and abruptly narrowed anteriorly close to the 

 head, which is very small, short, conical, and acute at the tip. On the 

 anterior thirty-two setigerous segments the feet consist of a small upper 

 ramus, having a small, tapering dorsal cirrus and a minute setigerous 

 lobe, bearing a small fascicle of slender and short setae, and a lower ra- 

 mus, separated by a narrow space, and consisting of a small upper 

 papilla, and a long transverse row of minute, rounded papillae, which 

 surmount a narrow, somewhat elevated, crest-like ridge; the first twelve 

 or thirteen segments having shorter rows, so as to leave a broad, naked 

 ventral space, but those farther back having rows of papillae that nearly 

 meet beneath, and thus entirely covering the sides and ventral surface 

 for a short distance; these crest-like ridges bear close rows of minute, 

 hooked setae. The branchiae commence on the upper surface of the fifth 

 setigerous segment, in the form of elongated papillae, which become 

 more elongated and narrow ligulate farther back. Posterior to the 

 thirty-second segment the papilliform crests of the lower ramus disap- 

 pear, and the lower ramus consists of an elongated papilliform, and finally 

 cirriform, upper process, with a minute setigerous lobe at its base, 

 bearing fine inconspicuous setae ; and an elongated membranous basal 

 portion, decurreut down on the lateral surface of the segment; the up- 

 per ramus is connected at the base by a membranous web with the lower 

 one, and consists of an elongated dorsal cirrus, similar in size and shape 

 to the branchia, and a very small setigerous lobe, bearing a small fas- 

 cicle of fine setae. The branchiae are connected by a slight web-like 

 basal ridge with the dorsal cirri. Thus there are three parallel rows of 

 cirriform or slender ligulate' processes along each side of the back, leav- 

 ing a broad, central, naked space all along the back. 



Length up to"60 mm or more; breadth, 4 mm . 



Savin Rock, burrowing in sand at low-water mark, May, 1872. 



Anthostoma. robustum Yerrill, sp. nov. Plate XIV, fig. 76. (p. 343.) 

 Body large, long, stout, thickest and rounded, or but slightly depressed, 

 anteriorly; tapering rapidly to the head; posterior portion very long, 

 narrowing gradually to the posterior end, flatter or concave above, well 

 rounded below, higher than wide, with three rows of long, erect, ligu- 

 late, or narrow lanceolate processes along each side of the back, the four 

 inner rows largest ; and a pair of foliaceous processes on the sides of 

 each segment. Head short, conical, acute. Proboscis large, broad, di- 

 vided into about eighteen long, narrow, digitate, and sulcated lobes, with 

 convoluted margins, broadest at the end, and free for a large part of 

 their length, but united at thebasebya membranous web; or it might be 

 described as divided into a lower, two lateral, and two upper main lobes, 

 each of which is again divided into three or four digitations. During 

 life these are all continually changing in form and length, and generally 

 only a few of the processes are protruded at one time. Branchiae com- 



