RHYNCHONERELLA PYCNOCERA. 149 



in length to the middle region of the body. The length of the sixth or seventh 

 somite is only near half that of those near the twenty eighth, in which region 

 the width is from three to three and a third times the length. In the posterior 

 region the somites continue of the same actual length as those of the middle 

 region, the relative length, however, being thus much greater. The segmental 

 organs first appear distinctly on the fifteenth somite, though on a few in front 

 of this they occur in a very rudimentary condition. They increase in size to 

 the middle region and gradually and but moderately decrease again in the caudal 

 region. 



The neuropodia in general are slenderly conical in form and long, the most 

 anterior ones, however, being much shortened. Each ends in a slender, distally 

 pointed appendage. The styles of the cirri are fohaceous and large like those 

 of Phyllodocidae. The notocirri have the cirrophores conspicuously large and 

 swollen. They are attached above at the base of the parapodium. The styles 

 of the anterior notocirri are broadly ovate, with apices acute. Caudad toward 

 the middle region they increase considerably in size and are proportionately 

 to the width somewhat longer. In the posterior region they become much 

 smaller. In all cases they extend beyond the distal end of the neuropodium; 

 and in the anterior and middle regions particularly are strongly imbricated. 

 The anterior neurocirri are ovate, acute; they are smaller than the correspond- 

 ing notocirri, but extend similarly beyond the neuropodia. In the middle 

 region the neurocirri are more slender than the notocirri, being broadly lan- 

 ceolate or oblong-lanceolate in outline. In the posterior region they become 

 reduced in correspondence with the notocirri, but still attain or extend beyond 

 the tip of the nem-opodium. (Plate 25, fig. 7, 8; Plate 26, fig. 3, 4). 



The setae of the first parapodium are of two kinds, a stouter and a more 

 slender type, there being in the specimen studied four of the former and six 

 of the latter. Both types of setae are composite. The stout ones are slightly 

 doubly curved, with the acute tip of the shaft directed to one side. The terminal 

 appendage is very fine. The slender setae are longer than the others, and their 

 appendage is also longer. Caudad the number of stout setae becomes reduced 

 normally to two or one. The slender ones at the same time increase greatly 

 in number and length. (Plate 26, fig. 5, 6). 



Locality. Between Peru and Easter Island: Sta. 4683 (lat. 20° 02' 30" 

 S., long. 91° 52' 30" W.). 300 fms. to surface. Surface temp. 70° F. 9 

 December, 1904. One specimen. 



This species is probably nearest to R. grubei (Greeff), with which it agrees 



