56 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 86 



at Torrey Pines, La Jolla, Calif., November 26, 1925, by Dr. O. F. 

 Cook and H. F. Loomis. Type: U.S.N.M. no 1311. 



Description. — Body about 14 mm long and 0.7 mm broad. Num- 

 ber of segments, 51. Color in life whitish gray. 



Head and first segments shown in figure 17, a and h. 



Segment 1 has the posterior edge distinctly emarginate medianly, 

 but the pronounced inflation of the dorsal surface immediately in 

 front of it hides much of the margin from above. 



From segment 5 to near the caudal end of the body the posterior 

 portion of the anterior subsegments is longitudinally marked with 

 channels nearly twice as long as wide, each usually containing a 

 rounded or oval pit behind; channels separated from each other by 

 a thin, raised ridge. On the anterior poriferous segments the lat- 



PiGDRH 17. — Odachurus petasatus, new genus and species : a, Head and segment 1, dorsal 

 view ; b, head and first two segments, lateral view. 



eral carinae are rounded swellings, but toward the middle of the body, 

 although low and not abruptly raised from the surface, they be- 

 come more definite in outline, being distinctly obovate yet not reach- 

 ing the back margin, as they do on several of the caudal segments, 

 where they project beyond the margin as acute teeth. Antepenulti- 

 mate segment with the two large dorsal ridges reduced in size but 

 strongly projecting beyond the back margin as teeth. Penultimate 

 segment less than half as long as the foregoing segment and without 

 dorsal ridges or lateral carinae. 



Last segment nearl}^ as long as the three preceding segments to- 

 gether, the thickened tip angularly rounded, projecting a little be- 

 yond the valves and with two small apical setae. Preanal scale at 

 least four times broader than long ; hind margin straight, front mar- 

 gin rounded ; process on each side inconspicuous. 



