■234 PROCEEDINGS OF THE ACADEMY OF [April, 



is very broadly elliptical in outline, the margin little limbate, the pos- 

 terior two-fifths separated by a deep notch on each side from the 

 anterior three-fifths, the former erect and with its margin finely den- 

 ticulated with from twenty to twenty-five teeth. One-fourth of the 

 remaining margin anterior to the notch forms on each side a rather 

 thick, narrow, spreading rim, the margin of which is quite entire or 

 merely slightly crenulated, not conspicuously toothed as in M. hiceps. 

 Anteriorly the cephalic rim is separated from the postero-lateral mar- 

 gins of the palpode by a pair of distinct radial furrows. The palpode 

 is very large and contributes easily three-tenths of the entire margin. 

 It is very broad and flat, with a smoothly curved anterior border and 

 rather more than one-third of the middle of its posterior border pro- 

 duced backward on to the head plate as a slightly elevated median 

 welt scarcely rising to the height of a ridge. On each side of this, 

 forming its lateral boundaries and the posterior boundary of the 

 lateral portions of the palpode are the deep sensory slits, U-shaped or 

 hooked, with the lateral limb the shorter. No furrows or other mark- 

 ings occur on the surface of the cephalic plate. 



The mouth is large and the lips prominent and pouting. A short 

 ■distance behind it is a transverse groove encircling the ventral half of 

 the peristomium and joining a conspicuous longitudinal groove which 

 begins at the lateral notch in the cephalic margin and passes along 

 the side of the peristomium, to end posteriorly in the circular furrow 

 which separates a complete narrow ring from the hinder part of the 

 •segment. Inasmuch as the posterior part of the peristomium is re- 

 tracted within the anterior margin of II, this ring is completely con- 

 cealed ventrally by the prominent half-collar developed in that posi- 

 tion on the latter segment. 



The next segment (II) is very short, its length not more than one- 

 half of its diameter; the posterior third is completely separated as 

 &, distinct ring; and the anterior margin is somewhat produced into a 

 collar, the ventral half of which springs into especial prominence 

 abruptly at the level of the setse. Somite III is about one-third longer 

 than II and similarly biannulated, but its anterior margin is not col- 

 lared. Thus far the skin is entirely glandularly thickened. 



The following six segments (IV to IX) are decidedly longer, about 

 equalling their own diameter, and the secondary furrow, while always 

 present, is in a more anterior position not far behind the middle. 

 While the three anterior segments are glandular throughout, the ones 

 under discussion have the glandular area confined to the ventral half 

 of the bod}^ and especially to the anterior ring in the vicinity of the 



