434 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



laterally, subtruncate posteriorly, broadest near the posterior end, some- 

 what narrowed to the anterior end, which is snbtruncate and rather 

 broad ; the lateral and posterior angles are well-rounded. Frontal an- 

 tennae small, very slender, equal in length to scarcely more than half the 

 breadth of the head. Eyes moderately large, situated near the lateral 

 angles, at about the posterior third of the head. Buccal segment large, 

 broader than the head, extending forward on the sides of the head be- 

 yond the eyes. Tentacular cirri unequal, the two inferior pairs much 

 shorter than the two superior ones; all are thickened or somewhat 

 swollen above the basal article, and then taper gradually to a slender, 

 acuminate tip. The two inferior pairs are nearly as long as the head, 

 the two superior ones about one-third longer; all have a well-de- 

 fined basal article. The second superior pair evidently arise from the 

 first body-segment. The caudal cirri are very small, scarcely project- 

 ing beyond the end of the body, and are of a short elliptical or oblong- 

 form, obtuse at the end. The branchiae on the anterior segments are 

 rather small, obovate, narrowest at the basal end, broadly rounded 

 distally, each with a distinct dark green spot in the middle ; farther 

 back they gradually become much larger and broader ; posteriorly they 

 become broad-ovate, broadest near the basal end and narrowed distally. 

 The setae are very long and numerous, in large fascicles, which project 

 far beyond the branchiae and ends of the parapodia. 



The ground-color of the body is pale green or greenish white ; along 

 the back are three rows of dark green spots, one row occupying the 

 median line, with a transverse elliptical spot on each segment; the lat- 

 eral rows are formed by a spot on the sides of each segment, just at the 

 bases of the parapodia. Each branchia has also a dark green spot in the 

 center, which gives the appearance of a dark-green line of spots when 

 the branchiae lie back in regular imbricated order. On the sixth, sev- 

 enth, and eighth body-segments there is an appearance of a broad, 

 transverse, interrupted band of dark green color, produced by an 

 increase in the size of the median dorsal spots, which become so large 

 as to coalesce more or less. When closely examined, however, this 

 band can be separated into its constituent spots, separated by paler in- 

 tervals. 



Vineyard Sound, Mass., 1882, in shallow water. 



This species is closely related to A.speciosa. It may be distinguished 

 by the more slender body ; the more heart-shaped head ; the longer and 

 narrower form of the branchiae; and by the different coloration, es- 

 pecially in wanting the clearly-defined band on the seventh and eighth 

 segments, seen in the latter. 



Castalia cincinnata Verrill, sp. uov. 



Body with about forty-six setigerous segments, thickest near the head, 

 tapering back to the narrow, caudal segments. Dorsal surface very con- 

 vex and prominent, with a median dorsal groove ; lower side flat. Para- 



