156 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxx. 



P^aniily BEYRICHIID.E. 



Genus BEYRICHIA McCoy. 



BEYRICHIA ? RADIATA Jones and Kirkby. 



Plate XI, fig. 5. 



Beyrichia radiatu Jones and Kirkby, Ann. and Mag. Nat. Hist. (5), XVIII, 

 1860, p. 257, pi. VIII, figs. 1, 2a, 21). 



Length l.Ofi nun., greatest height 0.67 mm., greatest thickness 

 about 0.5 mm. 



Valves somewhat oblique, hinge line long and straight, anterior end 

 rounded and denticulate, posterior margin obliquel^^ truncate, surface 

 of valves with two rounded tubercules situated on the dorsal half, one 

 on either side of a central depression, the anterior tubercule much 

 larger than the posterior one. Small papilla? arranged somewhat 

 scatteringly over the entire surface. A wide free rim or flange, often 

 marked more or less obscurely with radiating lines, overhangs the 

 ventral and posterior borders of the valves. Usually this rim is 

 delicate and nearly flat, but with age it thickens and sometimes, as in 

 the specimen illustrated, the postventral part presents a swollen 

 appearance. 



The Kansas specimens referred to this species differ in no essential 

 respect from some of the British examples tigured by Jones and 

 Kirkby. In the specimen here figured the radial lines on the flange 

 are verv obscure, but this condition is satisfactorily accounted for by 

 the obviousl}^ senile state of the example. 



■ Formation and locality. — Cottonwood shales, 2 miles east of Cotton- 

 wood Falls, Kansas. 



Bedotyiu'.—Q^i. No. 35638, U.S.N.M. 



BEYRICHIA 1 EMACIATA, new species. 

 Plate XI, fig. tj. ^ 



Length 1.10 mm., height 0.68 mm. 



Size, shape, and general expression about as in B. f radiata^ but has 

 an emaciated look, the surface of the valves ])etween the nodes being 

 more sunken and the ventral portion much less tumid though ridged. 

 A short, vertical cur\ ed ridge in the post-dorsal angle and a rim-like 

 >)order iilong the straight back and anterior end. The flange or frill, 

 which is bent outward at the edge, is not so wide as in B.f radinUi. 

 Surface finely punctate. 



With oidy separated valves adhering to shal(> it was not possible to 

 decide whether they are equal or overlapping. If equivalved, the 

 species belongs to the same genus as B. f radiata ; if inequivalved, 

 then it would he an uiuisual form of either Beyrichiella or Beyr'tchl- 



