NO. 3 HARTMAN : ORBINIIDAE, APISTOBRANCHIDAE, PARAONIDAE 263 



Collections.— 888-38 (1); 1256-41 (1); 1259-41 (1); 2026-51 

 (several); near La Paz, Lower California, Mexico (1, collected by 

 Jens Knudsen, February, 1955) ; Osoflaco and Oceano, San Luis Obispo 

 County, California, in dead Olive shells (many, collected by Conrad 

 Limbaugh, 1955). 



The dorsum is elevated through the fourth setigerous segment and 

 depressed to concave in segments farther back. There are 16 to 18 

 thoracic segments. The first 10 neuropodia are long and thick, with 

 their parapodial ridges flanked by postsetal fringe (fig. 1). Their neuro- 

 setae are of two kinds; there are 3 to 5 rows of yellow uncini distally 

 curved and transversely ridged (fig. 6), some of which are distally 

 hooded. They form palisaded series. The setae in the posterior row are 

 longer, distally pointed and have transverse series of fine spinelets along 

 their free length. There is no inferior fascicle of pointed setae. The 

 next 6 to 8 neuropodia are smaller and less elevated. The corresponding 

 notopodia have long, simple postsetal lobes and fascicles of pointed setae 

 (fig. 1). 



The thoracic neuropodial fringe is present from the first parapodium 

 as two or three lobes; their number gradually increases to 9 to 12 lobes 

 on middle and posterior thoracic segments. Ventral fringe forms a single 

 row of lobes across the ventrum where best developed. It is first present 

 as a pair of lobes on the eleventh, or not before the twelfth to fourteenth 

 segments; it increases to five lobes on the next, and 15 lobes, on the 

 fourth or fifth fringed segment. It is absent after thoracic segment 17 

 to 20. 



Branchiae are first present from the fourth or fifth setigerous seg- 

 ment and continue back to the end of the body; they are simple, lingu- 

 late and laterally fimbriated (fig. 3). 



From about segment 11 the uncini are replaced by dark brown 

 spears (figs. 1 and 4) ; the posterior pointed setae and inferior uncinal 

 rows remain as in front but are more limited in number. Thoracic 

 notopodia have full fascicles of long pointed setae and a close fascicle of 

 slender yellow embedded acicula. 



Abdominal notopodia are similar to those in the thorax but have 

 fewer setae. Furcate setae (fig. 7), numbering one to three in a bundle, 

 occupy the inferior position of the fascicle. In median and posterior 

 abdominal parapodia they increase in number to 6 to 10 and are ac- 

 companied by pointed setae. Notopodial acicula are embedded, pale 

 yellow, slender and number 2 or 3 in a close fascicle. Abdominal neuro- 

 podia have 4 to 6 slender, shorter setae and one or 2 slender embedded 

 acicula. 



