38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



bosus a somewhat Agnostid-like aspect that is completely lacking in 

 the type species. 



73,^^j._Holotype : U.S.N.M. 146031. Paratypes: U.S.N.M. 

 146032. 



Undetermined pygidia 



Several pygidia, undoubtedly belonging to the family Eodiscidae 

 and possibly to some of the named species, are described hereafter. 

 Possible assignments are suggested in some cases. 



"Undetermined pygidium No. 1 

 Plate 11, figures 17-21 



Available material. — Three examples. 



Description. — Pygidium of strong convexity especially in the trans- 

 verse direction. Axis strongly prominent, moderately tapered, reach- 

 ing the posterior border furrow, showing eight rings plus a terminal 

 section defined by exceedingly shallow furrows ; articulating half-ring 

 short (sag.), articulating furrow straight. Pleural regions convex, 

 laterally sloping down vertically to border furrow. Border very nar- 

 row, ventrally extended into 8 to 10 pairs of short, somewhat back- 

 ward-directed spines. Outline of border arched in posterior view. 

 Surface of test with very shallow puncta, not equally distinct in the 

 available specimens. Length of largest pygidium 4.4 mm, width 4,4 

 mm. 



Occurrence. — Collection cs-4. North Chatham. 



Discussion. — The narrowness of the border and the shallowly punc- 

 tate surface suggest the possibility that this is the pygidium of 

 Leptochilodiscus punctulatus.^ 



Disposition of material. — Figured specimens: U.S.N.M. 146033. 



Undetermined pygidium No. 2 

 Plate 11, figures 14-16 



Available material. — Three more or less complete examples. 



Description. — Pygidium with considerable relief. Axis prominent, 

 relatively wide, tapered to a rather sharp point, almost reaching the 

 posterior border furrow, composed of six rings plus a terminal sec- 



^ Copious material, collected from another locality after this paper was written, 

 unquestionably supports this assignment. 



