1904,] NATURAL SCIENCES OF PHILADELPHIA. 499 



Distylia rugosa n. s. (PI. XXXVIII, figs. 38 to 41.) 



This is a large, handsome species, somewhat resembling Bispira 

 polymorpha Johnson, but differing from that species in the fewer spiral 

 tm-ns of the branchial base, the greater number of branchial radioles, 

 the arrangement of the eyes, the form of the spatulate thoracic setae 

 and pick-shaped uncini and probably the deep rugous dorsal folds. 



Exclusive of the branchiee, the type is 67 mm. long, the width at the 

 posterior end of the thorax to the middle abdominal region being 8 

 mm. and the depth at the same points 6 and 5 mm. respectively. The 

 ventral ends of the stiff, cartilage-like branchial bases are prolonged 

 and spirally coiled, but make only 1^ tm-ns. The radioles, which reach 

 a length of 22 mm. at the dorsal and somew^hat less at the ventral end 

 of the series, arise to the number of 58 on the left, 55 on the right, in a 

 crowded, closely interlocking double row from the entire distal margin 

 of the basal lobes. Each is strictly simple and perfectly free from the 

 others to the base; the outer surface is rounded and the inner bears 

 the numerous barbs, which have a length about twice the diameter of 

 the radiole, in a crowded double series for its entire length except a 

 short naked terminal region. In this species the eyes are less perfect 

 but far more numerous than in D. polymorpha, the number on each 

 radiole approximating 100. They are very irregularly distributed in 

 groups on both margins, most plentifully on the distal half, where a 

 very constant group of large eye-spots occurs just proximad of the 

 naked tip. In the type the branchiae are pale-colored, each plimie 

 with three brown spots, one near the base and two m the outer half ; 

 the other specimen has the gills almost continuously pale reddish- 

 brown mottled with white, especially on the basal half. The palpal 

 membrane has a free margin completely encirclmg the bases of the 

 branchial radioles within. It extends around the sides of the mouth, 

 ventrad to which the two halves meet as a pair of vertical plates con- 

 tiguous to the middle line, and entering the ventral collar incision 

 partly join the somewhat swollen bases of the ventral collar lobes. 

 The tentacles are about as long as the basal branchial lobes, and have 

 the basal half broadly margined, the distal half filamentous. 



The collar is rather thick, stiff, flarmg and prominent throughout 

 its extent. The dorsal opening is equal to nearly | the body width at 

 the peristomium, with the broadly rounded dorsal lobes bounding it 

 slightly, curving around the dorsal side of the first pair of setae fascicles, 

 but free from them. The ventral opening is narrow but deep and, as 

 mentioned above, is partly occupied by the ventral prolongations of 

 the circumoral membrane; on each side of it are the short, broad and 



