1853.] 265 



(e.) U. cerinus. This species cannot be confounded 'w\\}ci flavtis ; it has much 

 less prominent beaks, more compressed disks, is proportionally longer, with the 

 hinge and basal margins more nearly parallel, while the color of the epidermis 

 and of nacre are very different. Mr. Lea seems to have hastily made them one 

 species, probably without having time or inclination to compare them. 



(fi.) TJ. complauatus^ Soland. There has been some controversy respecting 

 the original name of this species, but it seems clear that Solander had Say's 

 purpnreus in view when he described his species. He not only remarks that it 

 inhabits rivers in Maryland and New Jersey, but his description, " ovate, com- 

 pressed, with the front (posterior) margin straight, obliquely truncated towards 

 the cardinal slope, hinge with the primary teeth three-sided and striated," applies 

 very well to a common variety of Say's purpureifs. If Solander's name had 

 been founded alone on the figure in Lister, t. 150, fig. 5, it could not be retained, 

 because the species intended to be represented by that figure will probably ever 

 be disputed; and it represents U. niger, Rdif., much better than the shell in 

 question. Lamarck even quotes it for crasside?is, (Lea's trapezoides,) which it 

 certainly does not resemble. The words " admodum crassus," engraved on 

 Lister's plate, prove that it was an exceedingly thick shell, and a Western 

 species. 



(/.) Z7. clava. Kuster has quoted Rafinesque's figures 23 and 24 for his gibbosa, 

 w-hich is a nodulosus species not figured on any of his plates. Those figures 

 represent U. scaleuia. 



(g.) TJ. nodiferus, Con. Mr. Lea considers this identical with prasinux. 

 Since I have compared several specimens with a fine series of the latter species, 

 I see little resemblance between them. The nodiferus is a smaller, more ven- 

 tricose and inequilateral shell, and the large tubercles grouped together about 

 the middle of the disc, are never seen vd prasiniis. The latter has the slightly 

 prominent tear-shaped tubercles like the young qiiadrulus, very dissimilar in 

 number, shape and prominence to those of the nodiferus. Three specimens of 

 the latter, from Alabama, are in the collection of the Academy. 



(Ji.) U. ockraceus, Say. T. 157, fig. 12, in Lister's Conch., is usually referred to 

 A}wdo7ita cataracta of Say, but it much better agrees with the Southern variety 

 of U. ochraceus. The color, ' subruber," does not agree with any of our Ano- 

 dontas^ and, moreover, Lister names it Pectunculus, under which general term 

 he includes Galathea, Paxyodon and Cyclas, w'hich is sufficient evidence that 

 his Pectunculus fluviatilis had well defined teeth. The cardinal teeth of the 

 Southern ochraceus being distinctly striated, would account for the name of 

 Pectunculus being applied to it. Besides, it will be observed that Lister com- 

 mences the Auodontas with the heading of " Section 2d, De musculis cardine 

 laevi," which includes three species. His Section 3d then commences under 

 the heading of " Pectunculus." This is proof positive that his t. 157, fig. 12, 

 is not an Anodonta. 



(t.) U, oUiquus, Lam. Mr. Lea has referred Barnes' k?z^<2;^?,s to this species, 

 but Lamarck's description is wholly inapplicable to xindatus^ which is not 

 oblique, and certainly not " ovate-rotundate." The error probably originated 

 in Barnes' citation of Lamarck's species with a mark of doubt, as synonymous 

 with iindat^is. 



(j.) U. plexus, Con. There is a variety of this species, more elliptical, and 

 with the umbo and upper part of the disc covered with closely-arranged granu- 

 lations. It is possible that this may prove to be a distinct species. U. semi- 

 granosusy some conchologists think the same species with U. plexus, but it 

 certainly cannot be, if von dem Busch's species is represented in Phillippi's 

 Conchyi. pi. 1, fig. 1. That is a far larger shell, and of a totally different 

 character. 



(/t.) TJ. prasinus, Con. Mr. Lea observes that Prof. Kirtland thinks this 

 may prove to be a variety of pustulosus^ {hullatus, Raf.) They are, however. 



