102 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 25 



The modified ninth segment has mucronated setae of 2 kinds. One is 

 longer, slenderer (PI. 18, fig. 5), located at the outer ends of notopodial 

 and neuropodial fascicles; another is shorter, broader (PI. 18, fig. 4) 

 and occurs in spreading series in inner and medial parts of the fascicle ; 

 their arrangement is illustrated in Plate 18, fig. 6. 



Conspicuous pouched membranes, first present behind the modified 

 ninth segment, occur also between segments 10 and 11, and at irregular 

 intervals in abdominal segments. They are most developed at the sides 

 of the body, between successive parapodial outgrowths (PI. 18, fig. 1). 



Abdominal parapodia have broadly foliaceous, notopodial and neuro- 

 podial lobes (PI. 18, fig. 7) in lateral position, and transverse series of 

 long handled, hooded hooks. Dorsal and ventral cirri are very short and 

 easily overlooked ; they are located at the inner bases of the large para- 

 podial lobes. Hooded hooks have a large fang which is nearly at right 

 angles to the shaft, and surmounted by 2 much smaller teeth in a trans- 

 verse row (PI. 18, fig. 3). They are best seen by slightly rolling the 

 seta under a cover slip. 



Color in life is pale ivory with paired lavender spots on the dorsum, 

 most intense in the anterior region of the body, and usually within and 

 over the parapodial bases. 



Magelona sacculata differs from other species of the genus (see Hart- 

 man, 1944c, p. 319) in having conspicuous lateral pouched membranes; 

 the anterior margin of the prostomium is broadly rounded, and modified 

 mucronate setae of the ninth segment are of two kinds. 



This species occurs commonly in southern California, from Point 

 Conception to south of the Mexican border, in depths of 10 to 40 

 meters, usually in sediments of silt or fine sands. 



Family CIRRATULIDAE 



Key to Genera and Species 



1. Anterior end with a single median antenna .... 10 



1. Anterior end without a median antenna 2 



2. Some parapodia with composite setae 



Acrocirrus crassifilis 



2. Composite setae absent 3 



3. Anterior dorsal side with a pair of long, thick palpi, appear- 

 ing tentacular 4 



