1911.] NATURAL SCIENCES OF PHILADELPHIA. 313 



remain much as described, the presetal short and truncate, the post- 

 setal longer and acute. The notopodial presetal lip is obsolete and the 

 postsetal lip becomes much elongated, narrow and acute, with strongly- 

 constricted base. The postsetal lobes of both rami contain numerous 

 irregular long, longitudinal vascular loops quite different in arrange- 

 ment from those in the gills. Neurocirrus (fig. 173) a slender, pointed 

 process rising a short distance ventral to the neuropodium, obsolete 

 in the anterior region and becoming very small toward the caudal end. 

 Notocirrus wanting unless represented by the gills. 



Acicula of anterior parapodia apparently a large number of simple 

 tapering rods not easily distinguished from setae. On posterior 

 segments there are two or three notopodial and usually one neurc- 

 podial acicula, both very slender and tapered. On segments XIII to 

 XV, inclusive, appears a series of five to seven stout, brown spines in a 

 vertical row at the cephalic margin of the much reduced palisade of 

 setae and which are probably to be considered as modified acicula. 

 The dorsalmost (PI. XXI, fig. 174) is much larger than the others and 

 projects very prominently and obliquely upward across the interramal 

 space. At its base, as noted above, is a cirrus and large pear-shaped 

 gland. Like the largest of the others, only the tips of which are 

 exposed, the dorsalmost spine ends in a thickened, spearlike, acute 

 point. Among the large spines are some smaller ones with attenuate 

 tips. 



Setae are all simple and of one type in both rami, though differing 

 considerably in proportions and structural details. Omitting the 

 above-described spines, all are more or less acute, tapered and flexible. 

 Notopodial setae are generally longer and more slender and arranged 

 in dense fan-shaped fascicles on anterior somites and in delicate tufts 

 of a few setae on posterior somites. Neuropodials of the anterior 

 region form dense phalanges of four to six ranks in which the setae 

 increase in length and change somewhat in structure from before 

 backward. On the posterior region they form erect tufts of very few 

 setae similar in every respect to the notopodials. On the first few 

 parapodia notopodial and neuropoclial setae differ only in length. 

 Both are colorless and slender. The basal portion of the exposed part 

 contains a conspicuous spiral canal (PI. XXI, fig. 175) wound round 

 a central fibrous axis and more capacious on one side than on the 

 other, so that the axis is somewhat eccentric. Farther out the canal 

 becomes reduced and then obsolete on the side upon which it was 

 least developed, thus leaving an asymmetrical camerated structure, often 

 accompanied by a very minute serrulation which gradually disappears, 

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