106 THE ANNELIDA POLYCHAETA. 



dorsal depression. The venter is but little arched. It is traversed throughout 

 by a strongly marked neural furrow. 



Parapodia of the usual uniramous type, strictly lateral and very prominent, 

 throughout exceeding the depth of the body and over nearly the entire body 

 equalling the width of the somites. The first parapodium, i. e., of somite I, 

 represented by the neurocirrus, this being the first tentacular cirrus; that of 

 the second by notocirrus and nemrocirrus (dorsal and ventral tentacular cirri); 

 and that of the third is the first setigerous one. In this third parapodium the 

 notocirrus is a long tentacular cirrus; the neurocirrus is small as compared 

 with succeeding ones but is of similar. general form, being a flattened foliaceous 

 body, subelhptic in outline, and with the long axis vertical. A typical parapo- 

 dium, as, for example, the fortieth, has the setigerous division, or neuropodium, 

 flattened in the cephalocaudal direction; with the distal end obliquely truncate, 

 the dorsal angle being the more produced; the postsetal hp low and entire; 

 the presetal lip more prominent, divided by a notch near the tip of the aciculum 

 into the usual supraacicular and subacicular lobes. The neurocirrus is attached 

 by a very broad, low cirrophore to the base of the neuropodium; the style is 

 flattened and foliaceous but in comparison with that of the notocirrus small, 

 not fully attaining the end of the neuropodium, vertically elongate, with the 

 superior limb narrowed, the distal end blunt with its dorsal corner rounded, the 

 ventral one angular. The notocirrophore is enormous in comparison with the 

 ventral one, its width exceeding that of neuropodium and neurocirral style 

 combined; it is strongly flattened in the anterocaudal direction; its distal end, 

 broadly rounded, projects distad as far as the tip of the style of the neurocirrus; 

 strongly asymmetrical, its dorsal portion projecting farther and extending 

 dorsad. The style is subreniform, its edge evenly rounded excepting above, 

 where it is obtusely subangulate, the dorsal auricle not free and the ventral one 

 free for but a short distance. (Plate 16, fig. 4). Forward from the region of 

 the fortieth somite the parapodia decrease in size; the neurocirri become larger 

 in comparison with the notocirri, the style of each becoming relatively broader 

 and its tip surpassing that of the neuropodium; the notocirri retain the same 

 general form, but the cirrophore is narrower and shorter in comparison with the 

 neuropodium with its distal end less expanded, while the style in comparison 

 with the cirrophore is broader and its dorsal lobe larger and less narrowed toward 

 the cirrophore. (Plate 16, fig. 1-3; Plate 15, fig. 9). At the extreme anterior 

 end, beginning noticeably at about the seventh parapodium, the style becomes 

 conspicuously relatively more elongate above and subangularly narrowed, the 



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