NO. 2 HARTMAN : POLYCHAETOUS ANNELIDS 261 



Parapodia, in the anterior region, are provided with elongate, papillar, 

 dorsal and ventral cirri, and a single, larger, triangular, postsetal lamella 

 in the notopodium; a fifth parapodium is as shown in pi. 19, fig. 2. They 

 have numerous slender, pointed setae, the neuropodial fascicle much 

 smaller than, though similar to, the notopodial one. The ninth segment 

 is only about two thirds as long as the eighth; it has dense fascicles of 

 setae, nearly encircling the body at the sides, but leaving exposed a 

 median space dorsally and ventrally. Its setae are of 2 kinds in each 

 ramus. A few distalmost are longer, slenderer, with narrow wings (pi. 

 19, fig. 7). Most of them are shorter (pi. 19, fig. 4) and have a subdistal, 

 expanded wing with weakly crenulate margin and attenuate tip ; neuro- 

 setae (pi. 19, fig. 6) resemble notosetae (pi. 19, fig. 5). 



The tenth setigerous segment is only about two thirds as long as the 

 ninth, but as long as each of the next 4 segments. It and the following 

 segments are provided with broad, foliaceous, interramal lamellae (post- 

 setal in position) and dorsal and ventral cirri similar to, but smaller 

 than, those in front. Hooded uncini occur in spreading fascicles (pi. 19, 

 fig. 3 ) ; they are distally tridentate, the basal tooth large, the distal 

 paired (pi. 19, fig. 8), to be seen clearly only in frontal view (pi. 19, 

 fig. 9). 



M. pitelkai has the following combination of characters: the pro- 

 stomium is anteriorly rounded and dorsally grooved ; parapodia are pro- 

 vided with foliaceous lobes ; setae of the ninth segment are flattened sub- 

 distally; uncini are tridentate. M. papillicornis Miiller (Fauvel, 1927, 

 pp. 64-65) also has enlarged parapodial lobes, tridentate hooks, and broad 

 setae in the ninth segment, but the prostomial lobe and parapodial struc- 

 tures have diiiferent proportions, and the special setae of the ninth seg- 

 ment are distally mucronate, not crenulate. 



M. pitelkai inhabits muddy, sandy flats in low intertidal zones; the 

 substratum consists of smooth, fine-grained particles, probably little dis- 

 turbed by tidal action. Although soft bodied, species of this genus con- 

 struct no tube; they burrow through the substratum using the enormous 

 spatulate prostomium for digging. It is a pleasure to dedicate this species 

 to Dr. Frank A. Pitelka, who collected most of the specimens from 

 Tomales Bay, California. 



Holotype. — AHF no. 55. 



Type locality. — Tomales Bay, northern end ; at low water line. 



Distribution. — Tomales and Bolinas bays, California. 



