NEREIS LEUCA. 207 



The parapodia of the nereid division are of the common general form, short, 

 deep dorsoventrally, and in anterocaudal diameter narrowing distad. The 

 parapodia increase gradually in length caudad; but the relative sizes of the two 

 rami remain essentially the same. The rami short, the notopodial with two 

 short ligulae, the neuropodial with one. In the character of the notocirri 

 the anterior parapodia fall into two groups, as usual. Those of the first group, 

 consisting of but the first five pairs instead of the more usual seven, bear spe- 

 cially modified notocirri, each of these presenting a thick, subcylindrical body 

 narrowing at base and again abruptly distad to pass into a slender apical style 

 or tip. The remaining anterior parapodia have notocirri of the usual type, 

 the styles much more slender and tapering gTadually from base to tip. In all 

 cases the notocirri are attached close to the distal end of the notopodium, both 

 in the anterior and in the posterior group. As to the neurocirri, there are not 

 two such sharply defined groups as are frequently present. The first two pairs 

 are slightly more swollen at base than the others, but the transition is not so 

 abrupt as usual. The neurocuTi are all attached at base of neuropodia which 

 they exceed in the anterior pairs. They become relatively shorter in going cau- 

 dad. The parapodia of the heteronereid division are characterized, as usual, by 

 their greater length, which increases to the middle region of the division, again 

 gradually shortening caudad, by their greater relative thinness in the caudo- 

 cephalic direction, and especially by the laminate developments and the long 

 natatory setae. The notopodium is larger than the neuropodium and the 

 sinus between the two is rather deep. All the laminae are relatively smaller 

 than usual. The two ligulae of the notopodium have the usual relative size, 

 form, and position, the dorsal one being narrowly lanceolate, the ventral one, 

 attached by its edge on the ventral side of the ramus, is larger, distally acuminate, 

 and presents a distinct auricle proximally. Both laminae are much shorter 

 than the shafts of the setae, extending but little distad of the middle of the latter. 

 The principal lamina of the neurocirrus is narrowly subovate, distally narrowly 

 rounded, with the usual small auricle on each side proximally, the two auricles 

 asymmetrically placed with reference to each other. The dorsal neuropodial 

 ligula is small and more of the form of an ordinary style, being constricted 

 at base and narrowed to a point distad. It curves distad close to the edge of 

 the large lamina. The notocirrus is slender, tapered to a fine tip. It exceeds 

 the laminae, reaching to or beyond the ends of the shafts of the setae. On the 

 dorsal side of its base it bears a small, semicircular lamina attached at one 

 side. It is rather vaguely pseudojointed, but bears no distinct papillae along 



