314 THE ANNELIDA POLYCHAETA. 



Jaws rather thick, strongly chitinized. Caudal pieces of forceps-jaws, or 

 maxillae I, very broad, the greatest width of the two together clearly exceeding 

 the length, the ratio being about six to five. Each caudal piece or carrier is 

 roughly subtriangular, with the apex caudad, but with the ectal side convex and 

 even, the caudal end narrowly rounded, a median notch caudally between the 

 two pieces. A conspicuous thickening or ridge obliquely from anteroectal 

 corner to near middle of inner edge on each piece. Basal portion of forceps 

 constricted a little above base and widening gently distad, widest at distal end, 

 roughened with two curved ridges on face at proximal end. Distal division 

 stout, rather uniformly tapered, moderately strongly curved. Maxillae II 

 dark, blackish. Left outer plate with twelve or thirteen teeth, the inner with 

 eleven or twelve. Right plate with thirteen or fourteen teeth. Maxillae III 

 with nine teeth (left plate). (Plate 38, fig. 5). Maxillae IV with a single 

 tooth. Mandibles blackish back of the white masticatory plates, the stems 

 becoming pale brown to whitish. Masticatory plates large and oblique. Stems 

 narrowest cephalad of middle, gradually enlarging caudad, at the same time 

 incurving and in contact at the caudal end. The two halves separate. (Plate 38, 

 fig. 4). 



Of about a dozen tubes, the largest is nearly 265 mm. long, and 10 mm. in 

 diameter across the larger end in the longer direction, the lesser diameter across 

 this end being 8 mm. At the small end the large diameter is about 6.5 mm., 

 the smaller 5.2 mm. The tubes much resemble those of H. iuhicola. Each is 

 gently curved and tapered, and has an elliptical cross-section at all parts of its 

 length. The texture is quill-like, rigid, and translucent/ The tube is, as usual, 

 thickest over the middle portion, where the number of overlapping layers is 

 greatest, and thinnest and most easily collapsible at the large end, where the 

 most recent layer added projects from within the preceding. The usual annular 

 lines representing the exposed edges of successive layers are well marked through- 

 out the length. In the large tube, of which the measurements are given above, 

 the annuli are mostly from 4.5 to 6 mm. apart. 



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

 Depth 679 fms. Bottom of grey sand with black specks. Bottom temp. 38° F. 

 About a dozen tubes, half of them containing animals, were dredged 18 April, 

 1891. 



Off Mexico: Sta. 3425 (lat. 21° 19' N., long. 106° 24' W.). Depth 680 

 fms. Bottom of green mud and sand. Bottom temp. 39° F. A single specimen 

 taken 18 April, 1891. 



