SCAMMON : THE UNIONID.E OP KANSAS, PART I. 315 



lachrymose ; ligament black and conspicuous ; lunule dis- 

 tinct and well developed ; epidermis shining, painted with 

 a delicate dark mottling on a light ground ; hinge plate wide 

 and flat ; pseudocardinals heavy, triangular, blunt, ragged ; 

 laterals short, obliquely striated ; cavity of beaks not deep ; 

 adductor scars small, well impressed, those at the posterior 

 round ; nacre bright and silvery. 



"Animal with inner gills partly free from the abdominal 

 sac, rounded below outer gills, smaller marsupium consisting 

 of from seven to twenty-three very long purple ovisacs pen- 

 dant from the central base of the outer gills and formed into 

 a close coil with the ends turned inwardly ; branchial opening 

 large, with many small papillae; anal opening smooth." 

 (Simpson.) 



Cyprogenia alberti Conrad. Plate LXXI, fig. 2. 



Unio alberti Conrad, Proc. Acad. Nat. Sci. Phila., 1854, p. 295, pi. 



XXXVI, fig. 1. 

 Unio lamarcianus Lea, Trans. Amer. Phil. Soc, x, 1852, p. 256, pi. 



XVII, fig. 20. 



Unio popenoi Call, Bull. Washb. Coll., i, 1885, p. 48, pi. ll. 



Shell moderately large, very roundly triangular, com- 

 pressed, solid, thickest anteriorly. Anterior margin irregu- 

 larly rounded ; posterior margin gently curved, emarginate 

 posteriorly ; posterior margin short, slightly emarginate 

 centrally ; dorsal margin long, oblique, curved. Umboidal 

 ratio, 0.20 to 0.40. Umbones triangular, flat but fairly high, 

 pointed, plainly marked with the high but rounded umboidal 

 ridge, directed slightly forward. Anterior umboidal slope 

 fully rounded, lateral slope bearing a shallow but distinct 

 furrow ; posterior umboidal ridge high, distinct, spreading 

 out ventrally and rounded on both sides ; posterior slope 

 slightly excavated ; the umboidal third of the shell much 

 compressed. Shell sculpture consisting of several rounded, 

 concentric ridges toward the center of the disk and a series of 

 fine diagonal furrows above them in the lateral furrow. Epi- 

 dermis straw yellow with wide, dark rays of green, which 

 are curved forward, the spaces between the rays dotted with 

 minute triangular dots of green, which arrange themselves 

 at times into fine lines. Ligament long, thin, dark brown. 



