1904.] NATURAL SCIENCES OF PHILADELPHIA. 163 



very minute setse. The thoracic uncinigerous tori are strictly vertical, 

 and ventral to the setaj, and occupy an area on each side about equal 

 to the ventral plates. The abdominal tori are dorsal to the setse and 

 quite short. 



On somite I the collar setse are arranged in a double series along each 

 line. Those of the dorsalmost series (fig. 8) are stouter, nearly straight, 

 and are terminated by an elongated conical hood or sheath more or 

 less inflated at the base, and usually bent or wavy in the slender distal 

 half. They are evidently intermediate in structure between the pick- 

 shaped uncini and limbate setse. Those of the ventralmost series (fig. 

 7) are more slender, sharply curved at the end, and provided on the 

 convex side with a short but broad obliquely striated wing. The re- 

 maining thoracic somites contain curved limbate setse in the dorsal 

 part of the fascicles and paddle-shaped spatulate setse ventrally. The 

 former (fig. 9) present no noteworthy features. The latter are arranged 

 in close double file, those of the cephalic file (fig. 10) being stouter with , 

 very broad, truncate, usually more or less asymmetrical blades; those 

 of caudal (fig. 11) row have nearly circular blades, which usually bear 

 a smooth-edged mucronate tip as long as or slightly longer than the 

 blade. In the abdominal fascicles are 2 or 3 slender, nearly or quite 

 wingless capillary setse, and a small number of paddle-shaped setse (fig. 

 12), with small ovoid blades and a' prominent, stout, fringed terminal 

 process 2 or 3 times as long. 



There are about 60 of each kind of uncini in the thoracic rows begin- 

 ning with II. The avicular form (fig. 42) has the base straight, much 

 prolonged posteriorly, and with a small rounded breast. From the 

 base the short, somewhat tapering neck inclines forward at an angle of 

 about 120°. There is no enlarged head, but the vertex is high, promi- 

 nent and narrow, with the rather short, straight conical beak bent 

 down at a sharp angle. The crest is scarcely difterentiated, the front 

 of the vertex being only faintly striated and not at all subdivided. 

 Pick-shaped uncini (fig. 13) are well differentiated and regularly paired 

 with the larger ones. They have straight, column-like stems, and 

 hollow sheath-like heads (sometimes slightly inflated), running 

 into slender, tapering processes nearly at right angles to the stem. 

 The abdominal uncini are fewer, smaller, and have longer necks than 

 the thoracic avicular uncini, but are otherwise c^mte similar. 



The tube is slightly sinuous, nearly roimd in section and about 

 2.3 mm. in diameter. It has a peculiar tough horny texture, is thin- 

 walled and deep brown or almost black. 



From H. phwatccnia (Schmarda) Marenzeller this species differs 



