172 PROCEEDINGS OF THE ACADEMY OF [Jan., 



divided into two nearly equal halves, the proximal of which is soft and 

 longitudinally wTinkled, with a delicate ehitinous enclosing membrane, 

 the distal very firm and ehitinous, marked by 6 very narrow dark 

 ehitinous annular thickenings which have a slightly excentric arrange- 

 ment, as a result of which they are much crowded dorsally and more 

 widely separated ventrally, leaving a nearly circular, slightly excentric, 

 convex, pale-colored terminal disk. Probably the entire distal half, 

 with the exception of this disk, was originally covered with a calcareous 

 coat; rough fragments of such an incrustation remain especially 

 on the ventral surface. 



The collar is higher and its lateral lobes more prolonged than in V. 

 ctenophora, but is otherwise similar. The thoracic membrane is also 

 similar, but much higher, fully equalling the dorsal distance between 

 the setae tufts. As in V. ctenophora its base ends at the fifth seta tuft, 

 but a free lobe projects much beyond this to the seventh. 



There are 7 setigerous thoracic and about 110 abdominal somites, 

 the posterior ones very short and much crowded. For most of its 

 length the body is nearly terete, but at the posterior end is slightly de- 

 pressed and tapering. The extreme caudal end is slightly curved ven- 

 trad, so that the anus looks downward and is somewhat covered by the 

 posterior margin of the dorsal plate. The latter is much thickened and 

 of an ovate form, covering about 25 somites with the Inroad end tow^ard 

 the head. 



The thoracic setse are numerous, except in the collar fascicle, and 

 form conspicuous pale yellow tufts. Those of the first fascicle are 

 mostly wingless or nearly so, the limbate ones being more slender 

 and with the wings narrower than usual in succeeding tufts. On the 

 succeeding thoracic somites the number of wingless setse is much re- 

 duced, and most of them (figs. 29 and 30) are stouter and distinctly 

 limbate on the convex side and, while differing considerably in length, 

 curvature and breadth of wing, they have the wings const antl}^ wider 

 and more dehcately striated than in V. ctenophora. 



With the exception of those near the caudal end each abdominal 

 fascicle bears but three colorless setse (fig. 31) with slender stems and 

 rather broad but exceedingly thin and delicate blades. The ends are 

 tapering and curved, with a distinct angle at the base of the convex 

 side, which is fringed for f of its length. These setse are always stouter, 

 more angulated and less distinctly fringed than those of Vermilia 

 ctenophora, and the 3 exhibit a closer similarity of form and size. A 

 number (about 25) of the segments at the caudal end bear tufts of 4 or 

 5 long, slender, colorless capillary setse of a quite different form (fig. 45). 



