286 THE ANNELIDA POLYCHAETA. 



The peristomium is longer and wider than the prostomium, its anterior 

 border above and laterally being rounded down to the surface of the latter. 

 It is a little longer than somite II (6:5 in type), or sometimes equal to it. Its 

 surface dorsally and laterally is smooth. Down its anterior slope above there 

 is a median elevation that projects triangularly against the prostomium in the 

 usual way. On each side the margin protrudes forward broadly, convexly to 

 embrace the prostomium. The lower lip is set off on each side by a deep and 

 wide furrow extending from each side but little caudad of ventrad; its anterior 

 margin as a whole is convex, but at the middle is conspicuously excised, the 

 bottom of the excision straight, with a short sulcus running from each end of it 

 obUquely caudoectad. The cirri are short acuminate processes reaching to or 

 but shghtly beyond the nearest point of the base of the corresponding posterior 

 lateral tentacle. 



The first three metastomial somites form a more or less sharply separated 

 division of the body, characterized by a high, strongly convex dorsum, the fourth 

 somite being very much lower, and the third somite dorsally sloping from the 

 level of the second to that of the third. Caudad of the fourth somite the depth 

 of the body again gradually increases, but caudad of the anterior third again 

 becomes less, the body in the middle and posterior regions appearing typically 

 decidedly flattened. The first metastomial somites are widest across the 

 anterior end, as usual; the first in the type is two and a half times wider than 

 long; the second is longer, in the type a httle less than half (2.4:5) as long as 

 wide, the third is also of about the same proportions. The fourth metastomial 

 somite has the proportions of the first, being two and a half times wider than 

 long. In a paratype these first parapodia-bearing somites have the same length 

 and proportions. The somites from the fourth caudad are distinctly separated 

 above as well as laterally and ventrally. The somites increase in width to about 

 the fifteenth, then again narrow a little and remain nearly uniform over the 

 middle region, though the caudal region gradually narrows, with the caudal end 

 more abruptly acutely pointed. The fifteenth somite and adjacent ones, 

 measured across between bases of parapodia, are nearly four times as wide as 

 long, the somites in this and the following region being very short. The dorsum 

 over the somites caudad of the fourth is marked by longitudinal sulci, one each 

 side of the middle; between these the area tends to be lighter in color and the 

 anterior edge protrudes forward more or less and may appear notched where 

 crossed by each sulcus. There is a similar double sulcus along the ventral 

 surface setting off a neural stripe, with a slight median protrusion of the anterior 



