U N I 



Plate XGII. 



Species 498. (Copied from Lea.) 



Unio Lamarckianus. Uh. testa cmssii, depressa, in. 

 medio plunuldld, siihaqidluleraU, postice obtuse hiaii- 

 ijiilaid, iiifciiii nrcnald, hded, radiis viridibiis piinc- 

 talis luli-rntplis sidicateiialis (antice iiiajoribus) itii- 

 diijifc onidfd, i/icoHxjjiciie snbuodosn, aliter Ifevhjatd ; 

 costd nmboiiali obtuse aiigulatd, nntibus eiiiiueiitib/is 

 ad apices compresso-angidatis, marrjaritd albd ; dmti- 

 bus cardiuulibus mcgnis, compressis, creindalis ; Ja- 

 mdlis lateruUbus crassis, brevibus, reniotis. 



Lamarck's Unio. Shell thick, depressed, flattened in 

 the middle, subequilateral, bluntly biangulated be- 

 hind, arched below, yellow, everywhere adorned with 

 green dotted somewhat chain-like interrupted rays 

 (which are larg-er in front), indistinctly subuodose, 

 else smooth ; umbonal ridge bluntly angular, beaks 

 prominent, compressed and angular at the tips, nacre 

 white ; primary teeth large, compressed, crenulated ; 

 lateral lamellae thick, short, distant. 



Lea, Trans. Amer. I'hil. Soo. ser. i. vol. x. (Obs. on 

 Unio, vol. V. p. 22), pi. 17. f. 20. 

 U. AbiTii, Conrad, teste Conrad. 



Hub. Arkansas, America. 



Between irroridns and securis. The lines of growth 

 are very few, and the nodules are little more than rugosi- 

 ties disposed to run into small folds. 



Species 409. (Copied from Lea.) 

 Unio sagittiformis. Uh. testa teiiui, depressd, fere 

 siibcgguilaterali, oblique oblonf/o-eloiKjcdd, postice acii- 

 tamj/dai-i, ii/fente antice acclivi, Irsviyald, siibfascd, 

 radiis vireidibits latis undique profuse ornatd, costd 

 umhonali subacute angidatd ; area posticd dorsali 

 subpland, lird unicd radiante instructd ; natibus 

 parvis, proiuiuuUs, ad apices nudulatis, margaritd 

 purpurea ; dentibns cardinulibus compressis, creuula- 

 laiis, in ulrdque valculd 2 ; taii/ellis luteraHbus luiiyis, 

 recliusculis. 

 The AttROW-HEAD Unio. Shell thin, depressed, almost 

 subequilateral, obliquely elon^'ated-obloug, acutan- 

 gular behind, rising in front below, smooth, brown- 

 ish, everywhere profusely adorned with broad dark 

 green rays ; umbonal ridge somewhat acutely angu- 

 lated; hinder dorsal area ilattish, provided with a 



single radiating raised line; beaks smab, a little 

 projecting, undulated at the tips, nacre purple ; 

 primary teeth compressed, crenulated, two in each 

 valve; lateral lamellcB long, straightish. 

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



Unio, vol. V. p. 33), pi. 22. f. 35. 

 Ilab. Georgia, America. 



Approaches Fisheriauus, but is less elongated, and has 

 broader rays. The species was described from two speci- 

 mens only; the nacre will probably be found to vary. 



Species 500. (Copied from Lea.) 



ITnio persTRIaTUS. Un. testa lei/ui, pUinuUilo-snbcy- 

 lindricd, satis in/equilaterali, infiTui >iid)rclii\d ■ i-ni- 

 dermide fusco-liiled coucolorc, striis mullis ihihrica- 

 tis coHCenlric'e iiiKtnictd, uVder Imigatd ; costd um- 

 buuali plana et biamjuhdii, urea dorsali posticd lata 

 et planulidd ; natibus rix einiuentibus, ad apices ini- 

 iiulii uuJuhdis, margaritd albd, rarius purpuras- 

 cente ; deulibus cardinulibus parvis, obliquis ; lainel- 

 lis lateralibus longis, rectis, postice incrassatix. 



The thoroughly striated Unio. Shell thin, llat- 

 tened subcylindrical, moderately inequilateral, some- 

 what indented below ; epidermis of a uniform yel- 

 low-brown, furnished with numerous concentric im- 

 l)rieate(l stri;e, otherwise smooth; umbonal ridge 

 Hut and biiiiigulated, hinder dorsal area broad ami 

 flattened ; beaks scarcely raised, minutely undulated 

 at the tips, nacre white, very rarely purplish ; \m- 

 mary teeth small, oblique ; lateral lamella; long, 

 straight, thickened posteriorly. 



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

 Unio, vol. V. p. 11), pi. 12. f. 3. 



Hab. S. Carolina. 



The lines of growth are k\\. 



Species 501. (Copied from Lea.) 

 Unio satur. Un. testa crassd, tuuudd, valde in/vquila- 

 lerali, antice angustissimd (sed porrectd) , postice 

 subalatd truncatd et late biangidatd, Icevi, politd, 

 fused concolure (in junioribus, autem, olivaced), liga- 

 mento brevi crassoque ; costd uuibonali versus uates 



September, 18C8. 



