U N I 



Tlatf, LXXII. 



Species 36fi. (Mus. Hanley.) 



Unio eavistellus. Uii. testa parva, oblongo-subqiiatl- 

 ratd, Jiaiid pecidiariter hueqiiilaterati, compressiiis- 

 cuM, satis validd, ferriigiiieo-olivaced, mblavigatd, 

 minimi radiatd ; margine dorsali ulrinqiie angidato ; 

 margine ventrali coiivexo, margaritd alljo-livescente, 

 detitiliiis cardiuaJibus va/idis, liand lamiitatis. 



The little eusset Unio. Shell small, squarish-obloiig, 

 not very inequilateral, rathei- compressed, motlerntely 

 strong, ferruginous-olive, neither rnyed nor sculp- 

 tured ; dorsal margin angulated at each end ; ventral 

 margin convex, nacre livid white, cardinal teeth 

 strong, not laminar. 



MoEELET, Testae. Novis. vol. i. p. 29. 



Hah. Lake Ysabel, Guatemala. 

 There is no distinct umbonal ridge. 



Species 3G7. (Mus. Hanley.) 

 Unio stuiatulus. Un. testa parvd, solidd, si(bi-eiitri- 

 cund, subrhombed,fusco-oUvaced, hand radiatd, snblep- 

 rigatd ; margine dorsali utrinque siibdeclivi ; margine 

 n-iitrri/i coiwexiiiscnlo, antice arciiatim acclivi, ex- 

 Iriu.i'ilate posticd latiiiseuld, rotundnto-subbiangidatd, 

 vinryarifd (dbido-cferidesceide, dentibiis i-ardiiwlibus 

 miiijiris, laciniatis, hand transversis, dci/lifjiif: ln/eruli- 

 bii^ urciialis. 

 The si'RioLATED Unio. Shell small, solid, subventri- 

 cose, subrhorabic, olivaceous-brown, not rayed, 

 smooth or nearly so; dorsal edges slightly sloping; 

 ventral margin rather convex, arcuatedly rising in 

 front, hinder extremity rather broad, rotundately 

 sulibiangulated, nacre bluish-white, cardinal teeth 

 large, jngged, not transverse, lateral teeth arched. 

 Lea, Obs. on Unio, vol. viii. p. 59. pi. 2. f. 302. 

 Jfab. Roanoke river, N. Carolina, U. States, N. America. 

 Although the characters are chiefly negative, yet this 

 strong dwarf species can easily be recognized. The hinge- 

 margin is broad, and the inconspicuous umbonal ridge is 

 chiefly defined by the unsculptured concavity which fol- 

 lows it. 



Species 36S. (Mus. Hanley.) 

 Unio VELAEis. Ua. testa pared, tenui, compressiusculd, 

 jiallid} riridi, hand radiatd, sulilavigatd, extremitate 

 aiiilcd perangii^td ; latere posliro alato ; iiiarffiiii' ven- 



trali arcuato, aiitice sMto acclivi ; uatibits peracufis, 

 emiiientibus ; liaiuld excavatd, margaritd alba, deiiti- 

 bus cardiiialihus magnis, apprvximatis, lauiiiiatis. 



The sail-like Unio. Shell small, thin, rather com- 

 pressed, pale green, neither radiated nor sculptured ; 

 anterior extremity very narrow ; posterior side 

 winged, ventral margin arcuated, rising abruptly an- 

 teriorwards, beaks very acute, prominent, luiude ex- 

 cavated, nacre white, cardinal teeth large, lamellar, 

 approximate. 



Benson, in Hanley Eec. Bivalv. p. 3S5. pi. 23. f. 42. 



Uab. Assam. 



The abrupt fall of the front dorsal margin in this syni- 



phonote species gives a seeming projection to the beaks. 



Both dorsal edges are angulated above, and rounded off 



below; the hinder dorsal edge is much elevated. The 



compression of the valves is especially conspicuous on the 



anterior portion of the shell. 



Species 36'.». (Mus. Haidey.) 



Unio BOTUNDUS. Un. testa rolnndatd, untire. brevi el 

 angustd, postice. latissimd et subalatd, medio mibrenlri- 

 cosd, suhlfevigatd, superne uutem. rngis increinenti 

 tennilms elevatis concentrice scul/itd, mi/ro-oliraci-d 

 concolore ; margine dorsali antice valde dedivi, poslire 

 acclivi, utrinque angnlato ,- margine ventrali ralde ar- 

 euato, antice oblique acclivi, humid pernngustd, pro- 

 J'undii, natibus Jiaud eminentilnin, wurgarild alhidd, 

 dentihns cardinalibns laciniatis, transversis, dentihnx 

 lateralibus arcitaiis. 



The eounded IInio. Shell roundish, short and narrow 

 in front, somewhat winged and very broad behind, 

 subventricose in the middle, smoothish, yet closely 

 marked above in front with fine raised wrinkles of 

 increase, of a uniform dark olive-colonr ; dorsal edgi' 

 much sloping downwards in front, rising behind, an- 

 gulated at each end ; ventral margin much arcuated, 

 rising very obliquely in front, lunule very narrow, 

 profound, beaks not much elevated, nacre whitish, 

 cardinal teeth jagged, transverse, la'eral teeth much 

 curved. 



Spix, Test. Bras, pi, 2G. f. 3, 4. 



Hab. Brazil. 



The umbonal ridn'C is very indistinct. 



