NO. 1446. NEW PALEOZOIC OSTRACODA—FLRICH AND BASSLER. 151 



PARAPARCHITES HUMEROSUS, new species 

 Plate XI, figs. 1-4. 



Length of large example, 1.8 mm.; height of same, 1.25 mm.; thick- 

 ness of same, 1.05 mm. Carapace subovate, with the outline slightly 

 angulated in the antero-dorsal region; surface rather strongly convex, 

 with greatest thickness near middle of valves. Left valve with dorsal 

 edge straighter than in right valve, the edge in the latter being con- 

 vex in outline and thickened so that it projects above the hinge line 

 of the left valve. Ventral edge of carapace thick and sligntly chan- 

 neled on each side of the constant line between the valves. 



This species is distinguished from all known American Carboniferous 

 species referable to this genus, and from those from British rocks 

 described by Jones and Kirkb}^ as of Leperditai., except their L. eoni- 

 jwessa^ in the more ovate outline of its carapace. The valves of L. eom- 

 presxa, however, are much less convex, especially in the middle parts, 

 so that its carapace presents a veiy different outline in edge views 

 when compared with the comparatively evenly convex profiles pre- 

 sented in corresponding views of P. snhovatd. In all the other Car- 

 boniferous Leperditiidfe the dorsal line is straighter and one or both 

 of the dorsal angles much better defined. 



On account of the thickening of the dorsal edge of the right valve 

 and the rounding of the outline thereby produced, this valve may be 

 mistaken for valves of Cytherella like C. rlehteriana Jones and Kirkby 

 and O. inflata Jones and Kirkby. 



Formation and locaUtii. — Abundant in the Elendale formation, Man- 

 hattan, Kansas, and in 3^ellow shales of the Wreford limestone, (> 

 miles weyt of Reece, Kansas. The species occurs also in forms gener- 

 ally a little inferior in size to the Manhattan specimens, very abun- 

 dantly in the Permo-Carboniferous deposits of Texas, notably in 

 certain dark shaly limestone, on Mustang Ch-eek, east of Ballinger. 



Cotype8.—Q;9X. Nos. 35637, 35657, U.8.N.M. 



NOTES ON CARBONIFEROUS BEYRICHIID^ AND KIRKBYID^. 



The Carboniferous ostracoda that have been referred by authors to 

 the genus Beyrlclda are divisible primaril}^ into two unequal groups. 

 One of these, which of the two accords the more nearly with the 

 Silurian genotj^pes of the genus, has equal valves; the other, which 

 contains more species, has unequal valves, the left being the larger. 

 The first group embraces species like B. % radiata Jones and Kirkby, 

 an American example of which is here figured. In this and the other 

 species of this group, the surface of each valve presents but two 

 rounded nodes, one larger than the other. The smaller node is situ- 

 ated behind the median sulcus and well down toward the base of the 

 dorsal half of the valve. The larger node is placed more or less in 



