1903.] NATURAL SCIENCES OF PHILADELPHIA. 459 



more closely and crowd the neuropodium, the foliaceous character of 

 the dorsal cirrus disappearing. The first parapodiiim consists of a 

 neuropodium without setae, but bearing a long, slender, cirrus-like pre- 

 setal lobe, and dorsal and ventral cirri, w^hich differ from the typical 

 ones only in their smaller size. Posteriorly, beginning at about somite 

 XXXV, a small conical notopodiiun appears just ventrad and cephalad 

 of the dorsal cirrus. This bears setae at once, and, in relation thereto, 

 is divided into narrow presetal and postsetal lobes, of which the latter 

 is more ventrad, features which become more evident as the notopo- 

 dium increases in size toward the end of the anterior region. 



The first few parapodia of the posterior region are transitional in 

 form, but quickly become more foliaceous and assume the characteristic 

 structure which is typically developed on somite LXXV. Here neuro- 

 podium and notopodium are well separated by a wide interval, and 

 each bears its appropriate cirrus. The former is essentially as in the 

 anterior parapodia, but both lobes are much broader and more leaf -like, 

 the 2 divisions of the presetal more divergent, the dorsal considerably 

 the larger and both longer than the postsetal lobe ; ventral cirrus rela- 

 tively shorter. Notopodium about one-half length of neuropodium, 

 obtusely rounded, broadly attached, and not constricted at base; pre- 

 setal and postsetal lobes not prominent, the latter more ventral, so 

 that an oblique terminal notch appears in face views of the parapodium. 

 Dorsal cirrus rises from the base of the notopodium, and is directed 

 almost vertically dorsad; form similar to anterior cirri, but stalk 

 shorter. More anteriorly each lobe of the notopodium bears a slender 

 terminal papilla, that of the presetal being quite long and slender. 

 Toward the posterior end the two divisions of the foot become still 

 more widely separated, and both again more slender and less fohaceous, 

 while the dorsal presetal lobe of the neuropodium becomes more 

 prominent. 



The neuropodial setae are arranged in a single vertical fan-shaped 

 row, which spreads very widely in the foliaceous swimming feet of the 

 posterior or genital region, the number of setae corresponding closely 

 with the width of the lobe. All are of the same form, compound, wdth 

 very long stems, especially on the swimming feet, and slender, finely 

 pointed, and very delicately fringed blades, which are longest in the 

 middle of each bundle and diminish dorsally and ventrally. The figure 

 does not show the full side view of the blade. 



Notopodial setae similarly arranged in a fan-shaped vertical series of 

 correspondingly smaller spread; all simple, colorless, slightly bent and 

 curved, and tapering to an extremel3^ acute point; the surface marked 



