U N I 0. 



Plate LXXXIX. 



Species 477. (Copied from Lea.) 

 Unio Caldwellii. Un. testa hand magnu, sntk crassn, 

 v'u subijieequilaterali, satis compressd, elUpticd, fuaco- 

 lutescente concolore, cunfertim concentnce sulcata ; 

 casta umlonall pmdulmn. elevatd et rotmidatu; area 

 pos/icd durmli sidmiir/ii^id, lined impressd radiante iii- 

 di-Kctii : iKildiiis iiroiiiiiudis ad apices minute undidu- 

 lis, liiiiiihi aiKjnxtd, iiiaryaritd palllde nibro-aurnntid ; 

 dentibus cardiiulibus satis magnis, erectis, compressi-s, 

 creuidatis ; derdibiis lateralibiis siibrecds. 

 Calbwell's Unio. Shell not large, thickish, scarcely 

 inequilateral, tolerably compressed, elliptic, of a uni- 

 form yellowisli-brown, with close-set concentric sulci ; 

 umbonal vidge but slightly raised and rounded ; 

 hinder dorsal area somewhat narrow and furnished 

 with a radiating impressed line ; beaks a little pro- 

 jecting and minutely undulated at their tips, lunule 

 narrow, nacre salmon-colonred ; primary teeth toler- 

 ably large, erect, compressed, crenulated ; lateral 

 teeth straightish. 

 Lea, Obs. on Unio, vol. vii. (Jouru. Ac. Nat. Se. Philad. 



ser. 2. vol. iv.), p. 83. pi. 43. f. 145. 

 Hab. Isthmus of Darien. 



Described by Lea from a single specimen. The fur- 

 rows are less impressed posteriorly. 



Species 478. (Copied from Lea.) 



Unio pakallelopipedon. Un. testa oblongo-eloi/i/ald, 

 siihobliqnd, subcylind raced, iiiaquilalerali, crassiiis- 

 cidd, aiitice infenii acclivi, postice siibbianyidatd, sub- 

 Icevigatd, nigrescente concolore ; costd umboyiaU angii- 

 latd, iiatibus prominulis, plicis radiantibus ornatis ; 

 margaritd albidd ; dentibus eardinalibus obliquis, cris- 

 tatis ; lamelUs lateratibus rectis, elongatis. 



The parallelogram Unio. Shell elongated-oblong, 

 somewhat oblique, subcylindraceous, inequilateral, 

 thickish, in front sloping upwards ventrally, behind 

 somewhat biaugulated, smoothish, of a uniform 

 blackish hue ; umbonal ridge angular, beaks rather 

 projecting and adorned with radiating folds, nacre 

 whitish ; primary teeth oblique and crested ; lateral 

 lamellaj straight and elongated. 



Lea, Trans. Amer. Phil. Soc. ser. 2. vol. v. (Obs. on 

 Unio, vol. i.), p. 60. pi. 8. f. 20. 



Hub. River Parana, Corrientes, S. America. 



I Species 479. (Copied from Lea.) 



Unio Griffithianus. Un. testa oblongo-ellipticd, de- 

 pressd, sitbinfcijiiilaterali, crassiuscidd, autice porrectd 

 et angitstatd, attemiato-subbiaitgiilatd, inferrie sitbre- 

 tiisd, lilted, radiis obscure viridibus ornatd, natibiis 

 prominulis, costd umboiiali vix elevatd, mnrgarild 

 varid ; dentibus eardinalibus hand maguis ; lamellis 

 lateralibus loiigis. 



Griffith's Unio. Shell oblong-elliptic, depressed, not 

 very inequilateral, thickish, projecting yet narrowed 

 in front, taperingly subbiangulated behind, some- 

 what indented at the base, dirty yellow with obscure 

 green rays ; beaks somewhat prominent, umbonal 

 ridge scarcely raised, nacre variable; primary teeth 

 not large ; lateral lamellsc elongated. 



Lea, Trans. Amer. Pliil. Soc. ser. 2. vol. v. (Obs. on 

 Unio, vol. i.), p. 103, pi. L5. f. 46. 



Nab. S. Carolina. 



Allied to complanatiix, but more elongated. 



Species 480. (Copied from Lea.) 

 Unio hhomboideus. Uh. testa mugnd, tenui, compressd, 

 oblique subrhoinboided, vahh inaquilaterali, antic'e 

 inferne angitstatd, postice laid et subalatd, nitidd, 

 olivaced, aliquando obscure radiatd, concentrici sub- 

 slriatd; margine veutrali anlice acclivi, postice arcu- 

 alo ; costd nmbonali liuinili, viique rotundald ; artii 

 dorsali posticd peraiigiisld, radiisque biiiis linearibiis 

 ornutii ; iiatihiis ri.v proiiiiindis ml tipices minute un - 

 diiliili'i ; ii/iifi/iirilii iiiired, rel jiurj)iiruscente ; denti- 

 bus fseu poliiis luberciilis) eardinalibus compressis, in 

 utrdqiie valciild singulis ; lamellis lateralibus niillis. 

 The rhomboid Unio. Shell large, thin, compressed, 

 obliquely subrhomboid, very inequilateral, narrowrd 

 in front below, broad and somewhat winged behind, 

 glossy, olive, at times obscurely rayed, somewhat stri- 

 ated concentrically; ventral edge rising in front, 

 arched behind; umbonal ridge low and scarcely 

 rounded ; hinder dorsal area very narrow, adorned 

 with two linear rays ; beaks scarcely at all projecting, 

 minutely waved at the tips ; nacre golden-yellow or 

 purplish ; primary teeth (or rather tubercles) com- 

 pressed, one m each valve ; no lateral lamella.'. 

 Lea, Obs. on Unio, vol. vii. (.Tourn. Ac. Nat. Sc. Philad. 

 ser. 2. vol. iv.), p. 81. pi. 43. f. 143. 



September, 18G8. 



