NEW EXOTIC UNTONIDiE. 397 



epidermis yellowish olive, polished, obscurely radiate; nacre bluish-white and very 

 iridescent. 



Hob. — Bahia, Brazil, S. Moricand, Geneva, Switzerland. 



My cabinet and cabinet of M. Moricand. 

 Diam. 12, Length 2-1, Breadth 4 3 inches. 



Shell smooth, obliquely quadrate, slightly inflated, flattened at the side, very ine- 

 quilateral, obtusely angular behind, obliquely rounded before and very much gaping 

 behind and before ; substance of the shell very thin and semitransparent ; beaks 

 somewhat prominent ; ligament very long, rather thin and light-brown ; epidermis 

 yellowish-olive, greenish on the posterior slope, polished, obscurely radiate, with 

 distant marks of growth ; umbonial slope slightly raised and rounded ; posterior slope 

 narrow, compressed, with a somewhat elevated carina ; anterior cicatrices rather 

 large, confluent and very slightly impressed ; posterior cicatrices very large, con- 

 fluent and very slightly impressed ; dorsal cicatrices placed in the centre of the 

 cavity of the beaks ; cavity of the shell rather shallow and wide ; cavity of the 

 beaks very shallow and very obtusely angular ; nacre bluish-white and very irides- 

 cent all over the interior. 



Remarks. — Three specimens of this species were sent to me by Monsieur Moricand 

 many years since, under the name of anserina, Spix, but it cannot be the same 

 as described and figured in Spix's work on Brazilian Testacea under that name. 

 The Moricandii is much more oblong, is yellowish-olive and not " dark-green ;" the 

 valves are very thin and not " solid ;" the umbones are flattened and not " ventri- 

 cose." There cannot be a doubt but that this is not the shell described by Spix as 

 anserina, and I am much disposed to think that Spix's description and figure were 

 made of a middle-aged trapezialis, Lam. The Moricandii is more nearly allied to 

 Forbesiana, herein described, than to any South American species I know. It may 

 be distinguished by its outline not being quite so quadrate, by its being a much 

 thinner, lighter shell, and by its being compressed and having a light yellowish-olive 

 epidermis. All three of my specimens have the sides irregularlj- flattened, which 

 is very remarkable. The epidermis is very smooth and shining on the side, and 

 rough and dark-green on the posterior slope. The beaks of all are too much eroded 

 to satisfy me as to their being divergently undulate, but one of them has some indica- 

 tion of their being so. The eroded surface towards the tips has the nacre bluish. 

 The gaping of the anterior and posterior portions are quite remarkable for their size 

 and extent. I have great pleasure in dedicating this species to the memory of my 

 late lamented friend, Monsieur S. Moricand, of Geneva, to whom I am indebted for 

 it and many interesting fresh-water and land shells of Brazil. 



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