1906.] NATURAL SCIENCES OF PHILADELPHIA. 257 



are arranged in a half tubular figure at the base, from which they 

 diverge and spread distally in a fan-shaped fascicle. In each tuft the 

 shortest one (at the inner end of the posterior limb) is about twice as 

 stout as the longest. Distally they all taper regularly and rather 

 rapidly to very long, slender, acute and stiff tips. Except for these 

 tips they are striated conspicuously in both the longitudinal and 

 transverse direction. 



The ordinary set* (fig. 59) are few in number and form rather small 

 close tufts. They are apparently similar on all segments, being rather 

 slender with tapering stems and acute, tapering tips, striated some- 

 what obliquely, and provided on one side with a mng of moderate 

 width marked with distinct oblique striae. 



The uncini are numerous on the thoracic segments (135 on X). 

 They have the form shown in figs. 60 and 60a, being roughly tri- 

 angular, with large bases, a prominent superior ligament process, a 

 projecting rounded lower angle and long tooth-bearing border with 

 five or six strong acute teeth, the lowermost of which is peculiarly 

 bevelled and covers a short inferior ligament process which nearly 

 touches its lower surface. Abdominal uncini (fig. 61) are fewer in 

 number (78 on XXV), much smaller, and formed quite differently. 

 They have small bases and high outstanding tooth-bearing rami, and 

 apparently lack the inferior ligament process. 



Several thick-walled mud tubes in the same bottle were probably 

 fashioned by this species. 



Type locality. Queen Charlotte Sound, off Fort Rupert, Vancouver 

 Island, B. C, Station 4,201, 138 to 145 fathoms, soft green mud, sand 

 and broken shells. 



Chone gracilis sp. nov. Plate XII. figs. 62-66. 



A very pretty small species resembling Chone duneri Malmgren in 

 proportions but differing from that species in the short, and broadly 

 winged, barbless tips of the branchiae. From C. teres Bush this 

 species is easily distinguished by its much longer branchiae, small 

 number of abdominal segments and the more elongated form of the 

 abdominal uncini. 



The type specimen has a total length of 32 mm., of which the 

 branchiae make 12 mm. and the thorax 5 mm., the diameter for nearly 

 the entire length being about 2 mm. 



The branchial bases are simple and very low, being completely con- 

 cealed by the high collar. Ten pairs of delicate branchiae extend 

 equally to a length of more than one-half of the body. The stems are 

 united by a very delicate membrane for three-fifths of their length and 

 17 



