PETALOPROCTUS CRENATUS. 411 



there straight and transverse. The lateral portion forming an abrupt angle 

 with the dorsal and abruptly increasing in height, evenly continuous with the 

 ventral portion. The funnel thus appears to have an oblong piece cut out from 

 the dorsal side. The free edge of the elevated lateral and ventral region of the 

 funnel is distinctly crenate, the edges of the part bordering the dorsal excavation 

 smooth. Floor of funnel obliquely inclined, as usual, with the anus well toward 

 the caudal edge. (Plate 73, fig. 3, 4). 



Uncini of median and posterior segments moderately bent at neck ; shoulder 

 distinct; side beneath main hook straight, the opposite one convex. Hooks or 

 teeth normally four, of which the major one is wholly straight and is at right 

 angles to the adjoining edge of neck, the other three teeth being half erect and 

 decreasing in size toward the back of the crown, as usual. No subrostral tooth 

 or angle. Subrostral hairs six or eight in number. Minor hooks fibrous, 

 some fibers extending into the base of the major hook as well. (Plate 73, fig. 

 6, 7). On the penult somite of the type nine uncini were counted in the torus; 

 on the antepenult and adjacent somites the number varies from thirteen to 

 fifteen, the number rising to about twenty farther forwards. The major capil- 

 lary setae are slenderly acuminate, with exceedingly fine, long, smooth tips. 

 Below the tip in each there are narrow wings, or limbi, which are finely ribbed, 

 the oblique fibers appearing like series of closely arranged hairs. The limbi 

 disappear in the middle region in going proximad, where the shaft attains its 

 full width. Middle and proximal regions of seta wholly smooth. (Plate 73, 

 fig. 5). The finer setae have a similar structure and appearance, excepting for 

 smaller size. The medulla of the setae presents the usual fibrillar structure. 



The tubes are attached to partly carbonized fragments of wood, and have 

 a winding form, as usual, in one case being in part subspirally coiled. The tubes 

 are composed of fine grains of sand, among which are shell-fragments of Radiolaria 

 and Diatomaceae. 



Locality. Off the coast of Central America: Sta. 4631 (lat. 6° 26' N., 

 long. 81° 49' W.). Depth 774 fms. Bottom of green sand. Two incomplete 

 specimens and several tubes. 



This species resembles P. tenuis (Thcel) in having the margin of the anal 

 funnel crenulate or toothed, though the crenulations are missing anteriorly and 

 the funnel differs conspicuously in form from this and other known species. A 

 characteristic difference is in the presence of capillary setae on the last somite 

 and the partial coalescence of this with the preceding somite. Both the capil- 

 lary setae and the uncini also present characteristic features. 



