PHILIPPINE POLYCHABTOUS ANNELIDS 319 



this cirrus becomes a prominent ventral pad extending well onto 

 the ventral body surface. This condition continues as far as about 

 the fifteenth setigerous somite, and behind this region the pad grad- 

 ually becomes less prominent. On the sixth setigerous parapodium 

 the condition of the ventral cirrus is intermediate between that of 

 the fifth and the seventh. 



The first parapodium (fig. 3, b) has a very long conical postsetal 

 and much shorter presetal lobe, the latter having a vertical anterior 

 margin. The setal lobe is rounded dorsally but is cut away toward 

 the ventral end. The ventral cirrus is elongate lanceolate in form 

 from a narrow base and reaches to just beyond the apex of the setal 

 lobe. The dorsal cirrus is longer and slenderer than the ventral. 

 This parapodium carries slender, needlelike setae and much heavier, 

 hooked ones. In the tenth somite the setal lobe is small as com- 

 pared with that of the first and is turned upward at an angle of 45°. 

 The dorsal cirrus is long and slender; the ventral one has the pad 

 form earlier mentioned. A vertical row of sharp-pointed, rather 

 stout setae protrude slightly beyond the surface for the whole ex- 

 tent of the presetal lobe. Toward the upper end of this row are 

 a few pectinate setae. The gill has two branches, one of which is 

 long and slender. (Fig. 3, c.) The twenty-fifth parapodium has a 

 conical postsetal lobe, though this is small in comparison with those 

 of anterior somites. The presetal lobe has a vertical margin. The 

 dorsal cirrus and bill branches are all very long, the gill branches 

 being as long as the cirrus. Setae occur in a dense tuft. Near the 

 upper end of the tuft are a few pectinate setae; the others are 

 slender, some long and very slender, others bent near the ends. 

 (Fig. 3, d.) Two hooked aciculae came to the surface ventral to the 

 seta tuft. These did not appear in earlier somites. In the tenth 

 four large setae apparently function as aciculae. Each of these has 

 a heavy stalk that tapers abruptly at the apex to a short but very 

 sharp-pointed terminal portion. Smaller setae having approxi- 

 mately the same form are associated with them. These latter pro- 

 trude at the surface, their points forming a vertical row visible along 

 the margin of the upwardly directed setal lobe. A tuft of very 

 slender needle aciculae extends into the base of the dorsal cirrus. 



In the first parapodium occur a number of the same kind of setae 

 that Mcintosh 3 figures for O. (Nothria) will-emoesii and describes as 

 bifid. Those in O. branchiata (fig. 3, e) have one more subterminal 

 tooth than has willemoesii, and the terminal tooth is much sharper. 

 Mcintosh found them throughout the anterior region, but in the spe- 

 cies here described they do not occur as far back as the tenth somite. 



3 Mcintosh, W. C. Report on the Annelida Polychaeta collected by H. M. S. Challenger 

 during the years 1873-1876, Rep. Sci. Res. Challenger, Zoology, vol. 12, p. 322, pi. 26a, 

 fig. 1, 1885. 



