[nvertebrata from the Weocomian of Kansas. — Cragin. 7 
miter surface ornamented with thirty or more, slender, radial 
eostellae, the anterior three- fourths being devoid of concentric 
costelhe and marked with extremely delicate and crowded 
radial striae ; inner part of free margin delicately notched. 
or crenulatecl. 
The costelhe of the posterior part are not visibly echinate 
in the types. 
Measurements. — Hight 23 : length l'1 ; breadth 15 mm. 
Occu/rrenet — Moderately common in N<>. 5 of the Belvidere section, 
soul li of t In- rail way station. 
ROUDAIRIA QUADRANS. sp. nov. 
Plate I. figs. 14 and 15. 
Shell small, short, strongly elevated, triangular, the discs of 
moderate convexity; beaks situated considerably in advance 
of the middle, elevated. Bomewhat compressed on the anterior 
part and strongly so on the posterior, curved inward and 
downward and directed somewhat forward; no distinctly lim- 
ited lunule ; anterior and discal slopes flattish-convex, sepa- 
rated from each other by a broadly-rounded, scarcely appre 
ciable angulation, their outer surface marked only by ordinary. 
unequal, concentric growth-lines: posterior slope (about one- 
fourth of the valve) strongty flattened, separated from the 
discal slope by an abruptly rounded angulation, and orna- 
mented by numerous linear radial costelhe separated by 
grooves of about their own width. 
Measurements. — Hight50; length 47: breadth 30 mm., in 
the largest specimen. Most of the other specimens before me 
are relatively shorter and some of them much so. 
Occurn rece.— South wesl of Belvidere, in No. 3 of the Belvidere section; 
chiefly near the transition from No. I to No. 3. 
The exact number of radial eostellae is nol shown in i he types; Imt in 
the well-preserVed part of the striated area one example shows fifteen 
and iudicates apparently between tweutj and thirty for the full num- 
ber. Two of the type-specimens are much larger than thai selected for 
illustration, and one of these is of a short, elevated form, the other rel- 
atively longer, showing thai the shell is subjeel to considerable varia- 
tion. 
TAPES BELVIDERENSIS. sp. nov. 
Plate I. figs. 12, 13. 
Shell of medium size, ovate, or in elevated specimens tri- 
angular, ovate, tin- superior outline excavated in advance oi 
