: tfnjRAL SCIENCES OF PHILADELPHIA. 322 



December (5th. 



Mr. Lea, President in the Chair. 



Thirty-nine members present. 



Br. Fisher presented for publication an index of the genera described 

 or referred to in the Proceedings of the Academy, vol. i. viii., which 

 was referred to the Committee on Proceedings, with power to act. 



A paper was presented for publication in the Proceedings, entitled, 

 " Descriptions of Three New Species of Exotic Uniones, by Isaac Lea," 

 and was referred to a committee. 



Mr. Lea exhibited a specimen of Unio subrotundus, Lea, from White River, 

 Indiana, and observed that he had in May, 1836, called the attention of the 

 members to a female specimen of Unio multiplicatus, Lea, which had both lobes 

 of the branchia on both sides charged with embryonic shells. In the following 

 June, he exhibited a fine female, U. rubiginosus, Lea, also with the four lobes 

 charged. This species differed from the former in having red ova, which were 

 quite intense in color, resembling arterial blood. In July, 1859, he called at- 

 tention to a third species, U. Kleinianus, Lea, from Georgia, which had " a 

 branchial uterus in both lobes of the branchia on each side." These specimens were 

 in alcohol, and if the ova were red when living, it was not observable in those. 

 The specimens of subrotundus now exhibited, prove this species to be possessed 

 of branchial uteri in the four lobes of the branchia, and, also, that the ova are red, 

 like rubiginosus. Therefore, we now know of four species which have this 

 remarkable provision of a branchial uterus in each lobe or leaf of the branchia, 

 viz: 



Unio multiplicatus, 



Unio rubiginosus, 



Unio Kleinianus, 



Unio subrotundus, 



and of these, two at least have the very remarkable condition of redness of the 

 ova ; viz : 



Unio rubiginosus, 

 Unio subrotundus. 



It is a fact not less interesting, that the spermatic fluid of the male was found 

 in the glandular flattened lobules, also to be red, but the color did not appear 

 to be so intense as that in the ova of the female. Whether the males of other 

 species, the females of which have red ova, will be found to have red spermatic 

 fluid, remains for future investigation and observation. 



That other species will be found to have uteri in the four lobes of the bran- 

 chia he had little doubt, and that red ova would be found to characterise other 

 species is also probable. The coordination of the four species, as regards their 

 four branchial uteri, is very remarkable, and it is the more striking, as they 

 appear from their shelly covering their exo-skeleton to belong to groups yery 

 different in the structure of this part. The U. multiplicatus, and U. Kleinianus, 

 are both plicate; the former is the largest of the genus Unio known, and the 

 latter is among the smallest. The U. rubiginosus and U. subrotundus are smooth, 

 without any appearance of folds, and in their outline are different from the '.wo 

 former, and they also differ much, one from the other. In the four specie3 there 

 is such a marked difference in the shelly covering, as to cause the species to be 

 recognized at once as to their distinct normal forms. 



It has always been a difficulty, in the examination of alcoholic specimens, to 

 make exact and satisfactory differences in some of the soft parts, and these may 

 often be erroneously described where color or delicate organs and processes are 

 involved in the discussion of their characteristics. These difficulties can only 

 be avoided where the specimens can be examined in a living state, where all 



1859.] 



