ONUPHIS SOCIA. 289 



fine curved tip; below the tip the setae are biUmbate. (Plate 47, fig. 4). The 

 crochets are two in number; they are stout and have the usual slight double 

 curve distally; they are bidentate, the apical tooth being very small and erect, 

 the other one much larger and stouter, its upper edge nearly straight, its lower 

 convex ; the guards rise very slightly above the teeth and have the upper margin 

 straight or slightly incurved, long. (Plate 47, fig. 5). The pectinate setae are 

 strikingly different in form from those of the preceding species; from a delicate 

 fine stalk each very gradually widens distad, the enlarged blade being unusually 

 long and slender, and the setae as a whole somewhat oar-shaped. 



The maxillae are thin and mostly transparent, of a weak brownish tinge. 

 Maxillae I have the carriers forming a plate which is broad in proportion to 

 its length; the thickened triangular areas extend to the caudal incision, where 

 their acute apices end in contact; the thin plate caudoectad of this on each 

 side has the general form usual in this group of species, but it does not bulge 

 posteriorly, the lateral edge in front of the widely rounded caudal corner being 

 straight or diverging a little cephalad from the long axis. The blade on each 

 side is proximally veiy broad; it is abruptly narrowed well distad of its middle, 

 the narrowed fang being shorter than in the preceding species. Maxillae II 

 are long, narrow plates bearing on the right side thirteen acute and more or less 

 retrorse teeth, the most caudal of which is nearly at the caudal end; on the left 

 side the inner plate bears twelve teeth, the outer one, which lies close against 

 and parallel with the inner, bearing thirteen teeth. Maxillae III of the left 

 side bears eight teeth (or nine counting an obscure prominence at the proximal 

 end of the series) in a short, very slightly curved row, the right one bearing eleven 

 in a strongly cui'ved row. (Plate 47, fig. 2). 



The mandibles in the type have the masticatory plates hard and white, 

 oblique, with the inner ends much prolonged caudad and subacutely pointed; 

 the anterior margin has a single acute incision only, or with trace of a second one. 

 The stems are rather broadly united anteriorly; they are slender and unusually 

 long, and do not narrow caudad until near the caudal ends. (Plate 47, fig. 1). 



In the tubes the maximum length noted among those from Sta. 4672 was 

 about 400 mm., the maximum diameter 5 mm., while some tubes were but 3.5 

 mm. in diameter. The tubes have a tough, though thin, whitish lining membrane 

 outside of which is the thick layer of fine mud, which is greyish brown in color 

 but in part may have a slight greenish tinge. A tube from Sta. 4666 is 455 mm. 

 in length. 



Locality. Peru: off Palominos Light House. Sta. 4672 (lat. 13° 11' 



