ART. 12 A NEW POLYCHAETOUS ANNELID TREADWELL 6 



of the proboscis is broadest at the apex, and has on either side three 

 not very prominent longitudinal ridges. Its terminal margin carries 

 18 lobes. 



The parapodia (fig. 2) are similar in form throughout the body, 

 differing only in that the most anterior ones are ver}' small. The 

 setal lobe has the usual arrangem^'nt of a bifid presetal and a 

 rounded postsetal lip, the latter the shorter. The dorsal cirrophore 

 has nearly twice the vertical diameter of the setal lobe and is two- 

 thirds as long as it is. The cirrus is small and inconspicuous. The 

 ventral cirrophore is a rounded elevation at the base of the setal lobe. 

 The ventral cirrus is broadly rounded on its ventral margin and 

 distally bends upward and outward to meet the dorsal at an acute 

 angle. The dorsal margin is in general horizontal, but is more or 

 less wavy in contour. The apex of the ventral cirrus extends a little 

 beyond that of the setal lobe, and it is shorter than the dorsal cirrus. 

 The setae differ from one another only in size, the swollen apex of 

 the shaft carrying numerous spines (fig. 3). The distal portion is 

 long, slender, and slightly bent, and has numerous denticulations 

 along the concave surface. The holotype (Cat. No. 19244 U.S.N.M.) 

 was taken in the Gulf of Nicoya, Costa Rica. 



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