446 THE ANNELIDA POLYCHAETA. 



divided by a transverse furrow and much exceeding both the preceding and the 

 following somite in length. The third and immediately following setigerous 

 somites are sharply separated from each other dorsally, ventrally, and laterally. 

 Dorsally each of these somites is distinctly double, a deep transverse sulcus 

 separating off an anterior division from a longer posterior one, at the ends of 

 which the parapodia arise. The posterior dorsal division of the fifth setigerous 

 somite is crossed by a narrow, transverse, dark band, of which no trace is detectable 

 on other somites. Caudad of this the furrow dividing the somites becomes 

 weaker and in the posterior thoracic region is wholly absent, the line between the 

 somites also becoming weak. These posterior thoracic somites at the same time 

 increase very much in length in comparison with the anterior ones. The 

 abdominal somites are also very long in comparison with their width. The 

 sides of the thoracic somites project out abruptly just below the notopodia, 

 which in consequence appear to arise in a longitudinal depression. In front of 

 and opposite the upper end of the elevated lateral region of each thoracic 

 somite is a similarly prominent glandular area which becomes more elongate 

 caudad. 



The first parapodia are in the form of small, rounded tubercles. The 

 second are longer, while the third increase abruptly to much nearer the typical 

 size. A typical notopodium is subcylindrical, widening at base, narrowing a 

 little distad, and toward the distal end more abruptly so. Those of the longer 

 posterior somites are not increased in length. The uncinigerous tori begin on 

 the third setigerous somite. Each is a small, somewhat auricular lobe, attached 

 on the caudal side of the somite a little below the level of the notopodium. 

 The abdominal tori are situated at the caudal end of each somite. Each is a 

 thin lobe, short, and of moderate width, with the free distal margin straight or 

 weakly convex, and the width a httle less across the base than across the distal 

 end. 



The notopodial setae excepting on the most anterior somites much exceed 

 the notopodia. The setae are moderately coarse, with strongly fibrillated shafts. 

 Distally each is weakly bent, or geniculate, the region beyond the bend narrowing 

 distad and running out into a very fine tip which curves a little in the opposite 

 direction. Each is bilimbate from just below the first curve distad to the base 

 of the slender tip, the wings narrowing gradually to its ends. In a view at right 

 angles to the plane of the curve only one limbus is visible, this then appearing 

 rather broad. (Plate 79, fig. 8). The uncini are arranged in single series. 

 They are very small. Across the serrate edge there arc usually six scries of 



