30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



gidia usually show one or two small median nodes on the anterior 

 portion of the axis when the preservation is perfect. Length of largest 

 cephalon 8.0 mm, width 8.8 mm. Length of largest pygidium 8.0 mm, 

 width 8.0 mm. 



Occurrence. — Collection cs-4, North Chatham. 



Types.— UolotyT^e: U.S.N.M. 146014. Paratypes: U.S.N.M. 

 146015. 



OODISCUS BINODOSUS Rasetti, new species 



Plate 10, figures 16-18 



Available material. — Three cephala, of which only the holotype 

 well preserved. Pygidia may be present, but cannot be identified 

 among similar species of the genus. 



Description. — The cephalon is so similar to the type species that 

 only the differences are listed. Glabella narrower and of more 

 uniform elevation throughout its length, slightly longer, almost reach- 

 ing the anterior border furrow. Border furrow and border some- 

 what wider; anterior border bearing a pair of low, closely spaced 

 tubercles that somewhat encroach upon the border furrow. Lateral 

 border spines seemingly absent. Posterior border furrow straighter 

 than in type species ; geniculation with small, upright spine. Surface 

 of test smooth. Length of largest cephalon 6.5 mm. 



Occurrence. — Collection cs-4. North Chatham. 



Types.— Holotype: U.S.N.M. 146016. Paratypes: U.S.N.M. 

 146017. 



OODISCUS LONGIFRONS Rasetti, new species 

 Plate 10, figures 20, 21 



Available material. — A few cephala, none of which well preserved. 



Description. — Glabella of the same shape as in the type species, 

 but longer, just reaching the anterior border furrow. Border furrow 

 and border somewhat wider than in 0. subgranulatus; anterior border 

 furrow showing a slight median inbend where it merges with the axial 

 furrow; anterior border lacking nodes. Lateral border seemingly 

 lacking spines, but none of the specimens are well preserved enough 

 for this feature to be established with certainty. Geniculation of 

 posterior border as in the two preceding species. In the holotype a 

 pair of low, inconspicuous nodes is present on the downsloping 

 portion of the posterior border between the geniculation and the 

 genal angle, but this feature is indistinct in the paratypes. 



Occurrence. — Collection cs-4, North Chatham. 



