54 [March, 



Mr. Lea made some remarks on the subject of the periodicity of the Family 

 TJniouidcB. He mentioned that some of the species matured and ejected from 

 their oviducts the perfect shell in the autumn, others in the sprintr, and some 

 apparently in the winter. He mentioned that few observations had yet been 

 made on this interesting branch of animal economy. He had himself made some 

 observations many years since on the JJniones and Anodoiitcs of our vicinity ; 

 and his brother, T. G. Lea, had, at his request, made some interesting observa- 

 tions of those in the vicinity of Cincinnati, part of which had been noted in the 

 Transactions of the American Philosophical Society. He then read part of a 

 letter from Mr. Joseph Clark of Cincinnati, in vi'hich he mentions having ob- 

 served the ))eriodicity of several species within the last six months. Th*^ Ano- 

 doiita edentiUa^ Say, was found with oviducts fully charged in September, as 

 were also JJnio ellipsis^ Lea, Z7. irroratus^ Lea, U, securis, Lea, TJ. foliauis^ 

 Hild. and TJ. orhiculatus, Hild. In October he found the ova of the JJnio multi- 

 pllcatiis, Lea, more than half developed, and thinks they would have been ma- 

 tured in the spring. In the Unio aiiodontoides, Lea, they were beautifully de- 

 veloped, and would probably have been matured and voided in the winter. The 

 oviducts of the last species are bordered with a beautiful blue color. 



Thus Mr. Clark's conclusions were the same as to the different periods of 

 various species as Mr. Lea's, and there cannot be a doubt but that the terms of 

 the species differ according to their own law. 



March ZOtli. 

 Vice President Bridges in the Chair. 



The Committee on Mr. Lea's description of a new Unio, reported in 

 favor of publication in the Proceedings. 



Description of a new species of Symphynote JJnio. 



By Isaac Lea. 



Unio Chmingii. Testa alata, plicata, triangulari, valde compressa, postice 

 angulata, valde inaequilaterali ; ala elevata, acuminata, margine crenulata ; val- 

 vulis subtenuibus, ante et post nates connatis ; natibus, et alae posterioris basi 

 apiceque undulatis ; natibus compressis, ad apicem undulatis, baud prominenti- 

 bus ; epidermide nitida, tenebroso viridi, perradiata; dentibus cardinalibus la- 

 mellatis, lateralibus longissimis, lamellatis subcurvisque; ligamento celato; 

 magarita alba et iridescente. 



Shell alate, plicate, triangular, very much compressed, angular behind, very 

 inequilateral ; wing high, acuminate, crenulate on the margin ; valves ratiier 

 thin, connate before and behind the beak; beaks, and the base and summit of "the 

 posterior wing undulated ; beaks compressed, undulated at the tip, not promi- 

 nent ; epidermis shining, dark green, radiated all over ; cardinal teeth lamellar ; 

 lateral teeth very long, lamellar and somewhat curved; ligament concealed; 

 nacre white and iridescent. 



Habitat northern part of China. H. Cuming, Esq. 



Diam. .7, length 2.G, breadth 3.1 inches. 



This very beautiful and rare JJnio is, in form and general outline, very much 

 like the Dijysas pUcaticsy Leach, but they cannot be confounded with each other, 

 as they belong to very distinct genera, the Dipsas having but one linear tooth 

 in each valve, while the above described shell has perfectly well defined lamellar 

 cardinal teeth, double in the right and single in the left valve. It also has long, la- 

 mellar, lateral teeth, double in the left and single in the right valve. It differs also 

 in the folds, having them extending over the flattened side from the beaks, in this 

 specimen, which is not half grown, to half the length of the shell. The folds 



