256 [January, 



Mr. Conrad presented for publication in the Proceedings the following 

 papers, viz. 



1. Descriptions of three new species of Unio. 



2. Observations on the Eocene deposit of Jackson, Miss., with de- 

 scriptions of thirty-four new species of shells and corals. 



All of which were referred to a Committee consisting of Dr. Wilson, 

 Mr. Chas. E. Smith and Mr. Phillips. 



January 23J. 

 Vice-President Bridges in the Chair. 



A letter was read from Dr. Win. E. Dearing, dated Augusta, Georgia, 

 16th Jan., 1855, acknowledging the receipt of his notice of election as a 

 Correspondent. 



A paper was presented for publication in the Journal, entitled " Re- 

 marks on the Cryptogamic Flora of the State of Georgia, by Professor 

 Julien Deby;" which was referred to Dr. Zantzinger, Dr. Bridges and 

 Dr. Durand. 



January oOth. 



Vice-President Bridges in the Chair. 



The Committee on Mr. Conrad's papers, read Jan. 16, 1855, reported 

 in favor of publication. 



Descriptions of three new species of Unio. 

 By T. A. Conrad. 



UNIO. 



1. 77. Grandensis. Suboval, ventricose posteriorly, disks somewhat flattened ; 

 umbo distant from anterior margin, and with minute radiating lines extending 

 to- the tips of the beaks ; no concentric undulations; within purple. 



Locality. Rio Grande, Texas. 



Allied to 77. cardium, Raf., but differs in the striated beak, purple interior, &c 



2. 77. Tanmilapanns . Oblong, somewhat compressed; substance of shell thick 

 anteriorly and over the umbo; disks flattened; ligament margin nearly parallel 

 with basal margin ; umbo decorticated ; within pure white. 



Allied to 77. niger, Raf., but more regularly oblong and very white inside. 

 Locality. San Juan river, Taumilapas. 



3. TJ. Pearlensis. Suboval ; umbo ventricose ; sides contracted before the 

 umbonal slope, which is ridged or inflated ; two or three radiating folds poste- 

 riorly, most prominent over the umbo ; within whitish, with a purple margin. 



Locality. Pearl river, Miss. Prof. Thomas. 



Allied to 77. crasside?is, Lam., {trapezoides, Lea,) but proportionally much 

 shorter, more ventricose over the umbones, and less folded. This shell belongs 

 to my proposed genus Plectomerus, which, if without sufficient distinction in the 

 animal to constitute a genus, will form a convenient and very natural subgenus. 



