1905.] NATURAL SCIENCES OF PHILADELPHIA. 561 



segments are square, only the first 3 of the latter being again wider and 

 irregular. 



Except on the collar the thoracic seta tufts are oblique and linear, 

 nearly half as long as the corresponding tori, and each guarded by a 

 conspicuous anterior and posterior fold. Tori are relatively short, 

 little exceeding h the distance separating them ventrally, and of 

 remarkably uniform length, the second being slightly the longest and 

 those following decreasing in length to the last. On the abdomen the 

 uncinigerous tori and the setae tufts lie in nearly the same line, the latter 

 very slightly in advance of the former and but little shorter. 



The ffecal groove is well marked throughout both thorax and abdo- 

 men and passes obliquely across the right side of the first abdominal 

 and last thoracic segments for their entire length. 



Collar setffi are all of one form, capillary, acute, curved, narrowly 

 double-winged, not very long. The remaining thoracic fascicles are 

 composed of a small dorsal group of capillary setse similar to those just 

 described (fig. S) and a large number of broad-bladed spatulate setse 

 (fig. 10), forming a close phalanx of several vertical rows. Abdominal 

 setge are arranged in two vertical rows (about 15 in each on XX), the 

 one with short tips, the other with them more slender and about twice 

 as long (fig. 9). Koth have their shafts abruptly bent at the surface 

 of the body, where they are provided with short striated wings of 

 unequal width, beyond which projects the long, slender, acute tip. 



Thoracic tori contain the usual tAvo forms of avicular uncini and 

 pennoned seta, of which there are of each about 45 in each torus of V 

 and 30 on IX. On anterior segments the former have the form shown 

 in fig. 11, except that the beak is usually straighter. The body is long 

 and straight, the Ijreast moderate, the neck rather short, head large 

 and crest prominent and well forw^ard. On the last thoracic segment 

 the uncini (fig. 12) are very much larger and of quite different form, 

 the body being very long and slender, the breast very small, the neck 

 rather long and sloping forward, the head and crest small and the beak 

 less sharply bent downward. Anterior abdominal tori bear about 40 

 uncini (fig. 13) which are m\ich smaller than the smallest of the thoracic 

 and characterized by the small size of the posterior i)ortion of the 

 body, the large breast, and exceeding high and full crest. The pick- 

 shaped or pennoned seta (fig. 14) have short stems and slightly enlarged 

 heads with the usual hood and prolonged tip. 



Besides a slight tinge of brown about the parapodia, and, on some 

 specimens, 4 to 6 pairs of brown spots, diminishing in size posteriorly, 

 on the dorsum of II to V or ^TI, there is no pigment on the body. On 



