AMPHTCTEIS UNC OPALEA. 449 



The type-specimen has apparently been at some time partly dry. It is 

 widest at the anterior end just back of the first setigerous somite, where it has a 

 width of 4 mm. 



The prostomium presents above a subcordate elevation which is trans- 

 versely wrinkled, two of the furrows being deeper than the others. In front of 

 this elevation is a lower part crossed by two contiguous, submedian, longitudinal 

 ridges which extend to the mouth. Tentacles slender and cylindrical, not clav- 

 ate. (Plate 76, fig. 5, 6). 



The peristomium is produced into a distinct lower lip which flares out 

 ventrad along its distal edge. From near each anterolateral corner a furrow 

 curves caudomesad to the caudal border, the furrow being deepest caudad and 

 having its convexity ectad. A weaker transverse furrow connects these two 

 near the middle of the lip. (Plate 76, fig. 5, 6). 



The dorsum is strongly convexly arched and transversely finely striate. 

 The venter much less convex and somewhat flattened. The somites increase 

 conspicuously in length from the most anterior ones to the caudal end of the 

 anterior division of body. 



The fold between the branchiae is wide and conspicuously elevated, with 

 the anterior transverse arms moderately short. At the anterior and posterior 

 end is a pair of submedian, longitudinal sulci. (Plate 76, fig. 5). 



The paleae seem to be normally fifteen in number on each side, these all 

 well and uniformly curved throughout length excepting the slender capillary 

 tip, which is bent back into a hook or curved into a loop. Widely spreading, 

 ■ long, extending beyond head, the longest being 3.4 mm. long. 



The capillary setae are long and slenderly acuminate, as usual, with the wings 

 very narrow. The longest are about 2 mm. long, being thus much shorter than 

 the longest paleae. The uncini of the anterior region have a general form much 

 like that of those of ohscurior, but with only six teeth in addition to the rudimen- 

 tary one above the inferior process. The uppermost tooth is short and slender. 

 Dorsal edge proportionately long, longer than in either of the two other species 

 here recorded. (Plate 77, fig. 4). 



Locality. Off Mexico: Sta. 3424 (lat. 21° 15' N., long. 106° 23' W.). 

 Depth 676 fms. Bottom of grey sand with black specks. Bottom temp. 38° F. 

 18 April, 1891. One specimen, of which caudal portion is missing. 



This species is characterized among other features by the conspicuously 

 spreading paleae, which are uncinate or curled at distal ends instead of being 

 straight or nearly straight, as in the preceding species. The prostomium and 



