U N I 



Plate LXXXI. 



Species 425. (Copied from Lea.) 



Unio Houstonensts. Un. tedd subrotimdd, Mbbijlatd, 

 teqmlaierall, aiiiice paulisper depressd, crassiusculd, 

 Icevi, lideo-fuscd, vel concolore, vel rudiis obscuriori- 

 bus, margaritd alhidd ; denUbiis cardmalibus mngnis, 

 trectis, cremdaiis ; di-utibus lateralibiis ciirlis, siib- 

 reclis. 



The Houston Unio. Shell nearly round, somewhat 

 inflated, equilateral, a little flattened at the anterior 

 side, rather thick, smooth, yellowish-brown, either 

 without rays or with the rays obscure ; nacre white ; 

 cardinal teeth large, erect, crenulated ; lateral teeth 

 short and straight. 



Le.v, Proc. Ac. N. S. Philad. 18.59, p. 155; Obs. on 

 Unio, vol. viii. pt. 1. p. iO. pi. 60. f. 183. 



Hub. Houston and Rutersville, Texas, N. America. 



Nearly allied to petrinus of Gould, but its beaks and 

 hinder slope are not corrugated, the former being simply 

 marked by two or three folds. 



Species 426. (Mus. Lea.) 



Unio Showalteeu. Un. testa siibrotundd, crassd, sub- 

 lenticidari, (equilateral i, Itevi, tenebroso-fused, obso- 

 lete radiatd ; natibus eminentlbus, infatis ; marga- 

 ritd dbd ; deutibm cardinalibus crassis, erect is, com- 

 pressis, in utrdqiie mlvidd duplicibus ; dentibiis late- 

 raUbns brevlbus, percrassis, corrugntis. 



Showaeter's Unio. Shell roundish, thick, somewhat 

 lenticular, equilateral, smooth, dusky-brown, indis- 

 tinctly rayed ; beaks prominent, inflated ; nacre 

 white; primary teeth thick, erect, compressed, two 

 iu each valve ; lateral teeth short, wrinkled and very 

 thick. 



Lea, Proc. Ac. N. S. Philad. 1860, p. 307 ; Obs. on 

 Unio, vol. viii. p. 77. pi. 8. f. 223. 



IJab. Coosa river, Alabama. 



Nearly allied to circidas, but with higher beaks ; it re- 

 miiuls one also of ebenus, but has not the beaks recurved. 

 The dark brown epidermis inclines to bottle-green, with 

 obscure broad rays in the middle. 



Species 427. (Mus. Lea.) 



Unio pudicus. Un. testa subtriyond, inaquihderali, de- 

 pressd, siibcrassd, antice rotnndatd, postice obtuse an- 

 gulatd, nitidd, luteo-fuscd, radiis viridibus ornatd, 

 lavigatd ; natibus satis emiuentibus, ad apices ruyoso- 

 uiidtdatis ; margaritd alia; deidibus cardinalibus 

 crussiuscuUs, erectis, compressis, creuulatis ; dentibus 

 lateralibus subcurlis, crassis, subarcuatis. 



The modest Unio. Shell subtriangulnr, inequilateral, 

 depressed, thickish, rounded in front, bluntly angu- 

 lar behind, glossy, yellowish-brown, with green rays, 

 smooth ; beaks rather prominent, rugosely undulate 

 at the tips ; nacre white ; cardinal teeth rather thick, 

 erect, compressed, and crenulate; lateral teeth ra- 

 ther short, thick, and .somewhat curved. 



Lea, Proc. Ac. N. S. Philad. 1860, p. 62; Obs. on 

 Unio, vol. viii. pt. 1. p. 28. pi. 56. f 171. 



Ilab. N. Alabama. 



The rays are small and more fasciculate over the middle 

 of the disk, the umbonal slope slightly raised into an ob- 

 tuse angle, and the carinated posterior slope with few or 

 no rays. Its outline approaches rubiginosus, but is not 

 so triangular ; nor is it so angulated at the umbonal 

 .-ilope. 



Species 428. (Mus. Lea.) 



UiNIO TRINACRIS. Un. tesld in(Tqiidtderidi, oblique ovato- 

 trigond, crassd, ad umbones veutricosd, fusco-virente, 

 obscure radiatd, lavigatd ; area posticd luted et pla- 

 Hulatd ; rostd umbonali, conspicud, angulatd ; nati- 

 bus emineidibus, iiiargardd albidd ; margine cardinali 

 lata ; dcutibiis hderulibus subcurtis, percrassis, rectis, 

 corrugutis. 



The trident Unio. Shell inequilateral, obliquely ovate- 

 triangular, thick, ventricose at the umboes, brown- 

 ish-green, indistinctly rayed, smooth ; hinder area 

 yellowish, and flattened ; umbonal ridge angular and 

 conspicuous ; beaks prominent ; hinge-margin broad ; 

 lateral teeth rather short, very thick, straight, 

 wrinkled. 



Lea, Proc. Ac. N. S. Philad. ISGl. p. 59; Obs. on 

 Unio, vol. viii. p. 90. pi. 12. f. 235. 



Ilnb. Coosa river, Alabama. 



