NO. 2 HARTMAN : POLYCHAETOUS ANNELIDS 273 



Pista paclfica Berkeley 

 Plate 22, Figs. 37-41 ; Plate 25, Figs. 61, 62 



Berkeley, 1942, p. 202, figs. 1-3. 



Several individuals with tubes were taken from Tomales Bay, in 

 muddy sand flats, at low water line; the top of a tube comes from 

 Monterey, California, dredged from a few fathoms. 



This is large, long, tapering distally, with a total length of over 37 

 cm; number of segments is over 300. The thorax consists of 17 setigerous 

 segments, the second to seventeenth are also uncinigerous. Branchiae 

 number 3 pairs, are large, conspicuous, each with a long, thick base and 

 richly branched top; they diminish in size from the first to third pair, or 

 the second may be about as large as the first. 



The prostomium is bioad, rounded, directed forward in front of the 

 oral aperture. The lower lip, ventral to the oral aperture, consists of a 

 pair of prolonged, triangular lobes with ruffled edges; they resemble 

 lappets, but are united medially by a concave membrane. This segment 

 is continued dorsally as a short, smooth segment, immediately behind the 

 tentacle-bearing fold. No eyes or other pigment spots are visible. The 

 first branchial ring is smooth, short except for a minute lappet ventro- 

 lateral in position. The second and third branchial segments each has a 

 pair of broad, conspicuous lappets, longest at the dorsal ends. The follow- 

 ing segments have no lobes. Ventral scutes are conspicuous through 10 

 setigers, thereafter low, narrow. 



The first setigerous fascicle is small, located at the outer base of the 

 third pair of branchiae. From the second the fascicles are large, broaa, 

 resemble those following. Notosetae are light yellow, long, pointed, 

 narrowly bilimbate, with smooth edges. Uncini are first present from the 

 second setiger, occur in single rows in the first 6 tori, thereafter in double 

 rows. Those of the first series have a very long handle and terminate 

 distally in a single large tooth (pi. 22, figs. 37, 38). Farther back they 

 come to be gradually shorter handled and acquire a series of small teeth 

 above the main fang (pi. 22, fig. 39). However, throughout the thoracic 

 region they have a long handle ; one from the fifteenth setiger is shown 

 in plate 22, fig. 41. Abdominal uncini are short, with broad base (pi. 22, 

 fig. 40). 



Abdominal segments are smooth, with slight demarcation between 

 successive rings; their tori are short on the first few segments, increase 

 in length toward the mid region, but as the width of body diminishes they 

 are gradually shorter and smaller. Neurosetae are seemingly absent from 

 abdominal segments. Nephridial papillae are not visible save on the fourth 

 to sixth setigerous segment, where they occur as a thick papilla on the 

 posterior side of the setal fascicle. 



