HARMOTHOE MEXICANA. 55 



bases of the parapodia of 3.8 mm.; widths to tips of parapodia, G mm.; and to 

 tips of the setae, 8.2 mm. 



The prostomium in front presents two very large, conical peaks which pro- 

 ject forwards, one on each side of the median ceratophore. These peaks vary 

 considerably in the amount of their projection. There is a black area at the 

 base and caudad of each. Caudally the prostomium is rounded, expanding 

 from the caudal end to the middle and thus convexly bulging on each side. 

 There is a well-marked median longitudinal furrow from the base of the median 

 ceratophore caudad, and also a transverse furrow^ caudad of w^hich the pro- 

 stomium is typically more elevated. Two pairs of eyes of which the caudal 

 ones are dorsal and are much closer together than the anterior ones, which are 

 low on the sides or subventral and not typically evident in dorsal view. Each 

 lateral tentacle projects from beneath the peak of the corresponding side. Each 

 lateral ceratophore is attached beneath the base of the peak and projects ventrad 

 and is short and cylidric. The lateral tentacles are about as long as the pro- 

 stomium inclusive of its peaks. Each tapers uniformly from its base to the 

 very slender and acutely pointed tip. The ceratophore of the median tentacle 

 is a stout cylindrical body which narrows more or less distad; its distal end 

 is nearly on a level with that of the peaks. The palpi are about twice the length 

 of the prostomium. Each is terete and narrows uniformly distad to an acute 

 tip. There is no distinct terminal filament. (Plate 1, fig. 1). 



The parapodia of the peristomium have the usual position. The cerato- 

 phores attain or a little surpass the level of the most caudal point of the median 

 tentacular ceratophore but fall much short of attaining the level of the apices 

 of the prostomial peaks. The tentacular cirri taper evenly from base to the 

 slender tip and considerably exceed the palpi in length. Each parapodium 

 bears two, or sometimes three, stout setae resembling the notopodial setae of the 

 succeeding somites, each thickest proximally and narrowing distad to the acute 

 apex. (Plate 1, fig. 1). 



The metastomial somites are moderately arched above and below, the 

 ventral convexity sometimes appearing considerably more arched than the 

 dorsal. Ventrally there is a wide median furrow, most of which is occupied by 

 the neural ridge. Pygidium a small and almost tubercle-like projection. Anus 

 terminal. Nephridial papillae begin on the sixth somite as usual. They are 

 minute, short, subcylindric processes of whitish color projecting from a small 

 tubercle at the base of the parapodium. Each extends straight ectocaudodorsad, 

 or the somewhat longer ones of the middle region curving more dorsad distally. 



