1905.] NATURAL SCIENCES OF PHILADELPHIA. 563 



sparsely, the largest about 4 times the diameter of the stem, diminishing 

 in length toward the end, leaving a short thick tip of the stem naked. 

 Never more than 2 eyes, and sometimes one or none, occm- on each 

 stem. They are rather small, pale brown, regular in arrangement and 

 always on the proximal half and the dorso-median aspect of the stems 

 of the spread branchise. The oral membrane and tentacle are slightly 

 developed, the latter folded longitudinally. 



In most respects the collar is typical of the genus. The median 

 dorsal portion is better developed than in P. hrevibranchiata, but less 

 so than in P. oculijera (Leidy) ; the lateral portions are rather promi- 

 nent, rising abruptly from just above the collar seta^, and expanding 

 ventrally in broad, prominent lobes separated by the median ventral 

 fissure; on one side a deep notch, on the other a slight one bounds the 

 ventral lobe laterally. 



The form is generally slender and cylindrical, the thorax slightly 

 depressed anteriorly, narrower than the anterior region of the abdomen, 

 the posterior half of which tapers very gently to the pygidium, and the 

 anus nearly terminal but surmounted by a small lobe bearing two 

 groups of minute brown eye-spots. 



Thoracic setigerous tufts are prominent, the anterior especially 

 elongated and oblique. The uncinigerous tori are very little elevated 

 above the surface, the first and second longest, equalling about ^ the 

 circarnference of the body and separated by an equal ventral distance. 

 From the second they decrease in length, the last scarcely more than 

 ■J of the first and separated by a ventral distance of about ^ of the cir- 

 cumference. Abdominal parapodia are rather prominent, especially 

 the ventral setigerous ends, the first about equal to the eighth thoracic 

 and succeeding ones decreasing slowly but steadily to the last. 



The ventral glandular plates are narrow on the abdominal region, 

 separated from the parapodia by wide grooves and completely divided 

 into a pair of squares by the deep faecal groove, which turns to the right 

 obliquely across the first and appears again on the dorsum of the ante- 

 rior part of the thorax, where it opens into the dorsal fissure. It is not 

 visible on the posterior part of the thorax. The thoracic ventral plates 

 are indistinct and poorly developed in the type. 



No pigment is present on the greater part of the body, being confined 

 to 4 pairs of discrete reddish-brown spots on the dorsum of somites II 

 to V, which become successively smaller and the last mere specks. 

 Owing to the presence of great numbers of eggs the abdomen is some- 

 what yellowish. 



All setae have a pale yellow color. Those in the collar tuft are, 



