48 DESCRIPTION OF NEW 
number of minute impressions may be observed in both valves, posterior to the anterior 
cicatrix. Whether these are muscular attachments or not I am not certain; older and 
thicker specimens would enable one to judge. It has the triangular fosset common to 
the South American species. ‘The margin is broad for the size of the shell, and the 
granules of it are very perceptible with a microscope of good power. 
This species comes so near in its characters to the An. erispata, my specimen of which 
came from Cayenne, that it is with some hesitation that I have separated it. The ¢ortilis 
has the festooned crimples much finer, and they do not extend over the whole disk, 
as in the crispata, nor are they by any means so much impressed, but change into strie 
on the posterior slope and on the anterior portion of the disk. The /orti/is is also rather 
Jonger and more compressed towards the beaks. On the crispata the festooned crimples 
are much coarser, and the marks of growth are different. Dr. Gould, in the Proceedings 
of the Boston Society of Natural History, November, 1850, described an Anodonta, under 
the name of glauca, brought by the Exploring Expedition, which I believed at the time to 
be the crispata, Lam. The specimen seemed to me to be of the same species with that 
which I procured from Ferussac, in Paris, under the name of crispata. The name of 
glauca also is preoccupied by Valencienes, for another Anodonta from South America. It 
is with some hesitation I place this in the division of “ plicate” species, as it almost 
requires a lens to see the folds, but it cannot be called a “ smooth” shell. 
Anoponra Scnroreriana. PI. XXIX. Fig. 55. 
Testa levi, transversd, subcompressd, valdé inxequilaterali, postice obtuso-biangulari; valvulis subcrassis 5 
natibus prominentibus, acutis; epidermide rugosa, crebrissimé striata, tenebroso-oliva, obsolete radiata ; 
margarita alba et iridescente. 
Shell smooth, transverse, rather compressed, very inequilateral, obtusely angular behind ; valves rather thick ; 
beaks prominent and pointed; epidermis rough, thickly striated, dark-olive, indistinctly radiated; nacre white 
and iridescent. 
Hab. Rio Negro, Brazil, Mr. C. M. Wheatley. 
My cabinet and cabinet of Mr. Wheatley. 
Diam. .9, Length 1.5, Breadth, 3.1 inches. 
Shell smooth, transverse, rather compressed, very inequilateral, obtusely biangular 
behind, slightly compressed on the sides near the middle of the dorsal line, with a slight 
callus under the beaks; substance of the shell rather thick ; beaks prominent, pointed and 
placed towards the anterior margin; ligament long and rather thin; epidermis very rough, 
covered with very close crimpled stric, dark-olive, with a few indistinct rays over the 
posterior slope, and with rather distant lines of growth; posterior slope long, compressed 
into a carina; umbonial slope slightly raised and rounded; anterior cicatrices distinct, the 
smaller one very minute; posterior cicatrices confluent; no visible dorsal cicatrices; pal- 
leal cicatrices slightly impressed; cavity of the shell rather shallow and wide; cavity of 
the beaks shallow and angular; nacre with minute strie from the beaks towards the mar- 
gin, white and iridescent. 
Remarks.—A single specimen, or rather the two valves of different individuals, was 
kindly given to me by Mr. Wheatley. It does net seem to have been noticed by Spix or 
