276 THE ANNELIDA POLYCHAETA. 



sulcus that runs obliquelv caudomesad; its anterior border is straight and 

 smooth. The cirri are very small, distally pointed processes not reaching the 

 middle of the prostomium or the base of posterior paired ceratophore. (Plate 51, 



fig. 1). 



The anterior metastomial region is high, dorsally strongly convexly arched, 

 but ventrally flat. The height rapidly decreases to the fifth (fourth parapodial) 

 somite, caudad of which the somites are strongly flattened dorsally as well as 

 ventrally. The first three podous somites are only rather vaguely separated 

 from each other above; each is widest across the anterior end at level of origin 

 of the parapodia from where it narrows caudad, and is two thirds as long as 

 wide at that level. The fourth somite is abruptly and relatively shorter, the 

 succeeding somites remaining similarly short but gradually increasing a little 

 in width to about the tenth, from where the width does not vary much until 

 toward the posterior end. The fourth, fifth, and irranediately succeeding 

 somites are only about half as long as wide. The intersegmental furrows con- 

 tinue to be faint, excepting laterally, between the parapodia. There are the 

 usual thickened, whitish glandular areas below the level of the parapodia, the 

 integument elsewhere rather thin and semitranslucent. 



The parapodia in the anterior region are but moderately prominent struc- 

 tures, becoming shorter caudad. They begin on somite II near the ventral 

 level and occupy the same position on III and IV. With somite V they begin 

 a shift dorsad and at somite X they have attained the dorsal level. The first 

 two pairs of parapodia, which are attached at the anterior end of their somites, 

 slope strongly forward. The third parapodia slope forward less strongly and 

 the fourth extend straight out. On the remaining somites the parapodia are 

 attached near the middle of length and are much shortened. The first para- 

 podia are rather stout. Each bears a notocirrus, neurocirrus, and, between 

 these, a setigerous lobe which presents a low and inconspicuous presetal Up and 

 a moderately elongate, subcirriform, postsetal Up which is, however, much shorter 

 than the notocirrus or neurocirrus. The neurocirrus arises on the ventral 

 surface near the base and reaches to or a little beyond the base of the postsetal 

 process. The notocirrus arises on the dorsal surface nearly opposite the nexiro- 

 cirrus; it is constricted at its base, swelling out above this and then tapering 

 to the distal end; it is of about the same length as or but Uttle exceeds the 

 neurocirrus, but it is soniewhat stouter; they fail decidedly of reaching the 

 middorsal line. (Plate 51, fig. 7) . Caudad of the third pair the parapodia proper 

 rapidly decrease in size, and the style or process proper practically disappears. 



