492 PROCEEDINGS OF THE ACADEMY OF [May, 



to uncini, but the slender setae do not altogether disappear until about 

 LXXV, from which point backward the uncini become stouter and the 

 number gradually reduced to from one to three in each parapodium. 



The jaws are coarse, black and very brittle. The mandibles (PL 

 XXXVn, fig 22) are pale, stout and broad, with the two halves 

 strongly united, especially by transverse striated bands across the end 

 pieces. The bases are broad and roughly lammated. 



Much of the original color has been lost, but the head and anterior 

 region of the body retains a rich bronze with a beautiful blue and 

 green iridescence; the posterior part is dull brown, due to heavy 

 masses of pigment which are scattered everywhere through the deeper 

 integument, but especially in a narrow transverse band and a pair of 

 dorso-lateral spots on each somite. 



Cirratulus spirabranchus n. s. (PL XXXVIII, figs. 26 and 27.) 



Form rather stout, thickest in middle and tapering almost equally 

 both ways. The type is 105 mm. long and 5.5 mm. in diameter at the 

 widest part. Prostomium elongated, pointed and slightly depressed, 

 wdth a short oblique groove on each side above and near the union 

 with the peristomium. No eyes visible. Peristomium enlarged, its 

 length equal to six succeeding somites, somewhat irregularly divided 

 into three or four rings of which the last is much longer than the others. 

 There are about 300 setigerous somites, of which the first three or four 

 are longer than the others. Nearly terete, but slightly flattened ven- 

 trally where the muscle coats are considerably thickened particularly 

 toward the ends. All somites clearly marked, but short and uniannu- 

 late. The anus is a large dorsal slit reaching through 7 or 8 faintly 

 marked somites and followed by a minute tubercle-like pygidium. 



The branchiae are numerous and crowded and usually more or less 

 spirally coiled. They differ much in size, probably, however, only as 

 a result of loss and regeneration, but their length does not exceed 

 about five times the diameter of the body. Beginning with the first 

 setigerous a pair occurs on every somite except the last thirty, arising 

 immediately dorsad of the notopodial setae or from the margin of the 

 elevated band just above them. On the seventh setigerous somite 

 occur the special branchia? in a pair of dense tufts of about 20, arranged 

 in two transverse rows which nearly meet medially. They are mostly 

 smaller than the ordinary branchiae, and owing to the crowding of this 

 region usually appear to cover two somites, either VII and VIII or 

 VIII and IX." 



The setigerous tubercles (PI. XXXVIII, figs, 26, 27) are separated 

 by a smooth space about 3 or 4 times as broad as they, and both are 



