NATURAL SCIENCES OF PHILADELPHIA. 51 



February Wth. 

 Mr. Lea, President, in the Chair. 



Forty-nine members present. 



A paper was presented for publication, entitled : 



" Descriptions of new species of Cyrena and Corbicula in the Cab- 

 inet of the Academy of Natural Sciences of Philadelphia, by Temple 

 Prime. 



Mr. Lea remarked that when Mr. Binney, at the last meeting, called the at- 

 tention of the members to a reversed Paludina on the table, the discussion tak- 

 ing a wide range, he (Mr. Lea) stated that an abnormal reversed character 

 sometimes occurred in the genus Unio, and he then mentioned that hehad spe- 

 cimens of various species where this condition was very remarkable. He also 

 then stated that among Helices, in a semi-domesticated position in gardens, 

 hedge-rows, &c, in England and on the continent it was not a very rare cir- 

 cumstance to find heterostrophe individuals; he had quite a number; but that 

 among the immense number of our own species which had passed under his 

 eyes, he had found only a single specimen which was heterostrophe, viz. : a 

 Helix hirsuta, Say. Mr. Lea went on to say that he had prepared himself to ex- 

 hibit, to-night, his specimens alluded to, and to which he now called the atten- 

 tion of the members. He was glad to see by the December number of the Pro- 

 ceedings of the Boston Soc. Nat. Hist, received by post to-day, that Prof. Agas- 

 siz had made a communication to the Society on "reversed bivalve shells," ex- 

 hibiting a specimen of the Unio ligamentinus, Lamarck, observing that " it was 

 quite rare and generally not easily observed." Mr. Lea exhibited twenty-one 

 specimens of various species which were all abnormal as regarded their lateral 

 teeth, some having a single one in both valves, others being simply reversed as to 

 the double and single cardinal and lateral teeth ; others having double lateral 

 teeth in both valves, and others again having a treble lateral tooth in the left 

 valve, and a double one in the right valve. The first reversed Unio he had seen 

 was a specimen of complanalus from the mill-dam at Bristol, Penna., about 25 

 years since ; afterward he had found one in the Schuylkill, and subsequently 

 found them occasionally among thousands of specimens sent by friends from 

 various parts of the United States. From Dr. Lewis, of Mohawk, he had re- 

 ceived some very fine specimens. 



The following table will exhibit the various abnormal forms of Uniones in 

 Mr. Lea's collection : 



Single lateral tooth in each valve. 



Unio complanalus, Lea, (Mya complanata, Solan.) Schuylkill River, Pa. 

 " occidens, Lea, Wisconsin. 

 " purpuratus, Lam., Claiborne, Ala. 

 " ventricosus, Bar., St. Lawrence, Montreal. 



Single lateral tooth in the left, and double in the right valve. 



Unio complanatus, Lea, 2 specimens, Bristol, Pa., and Mohawk, N. Y. 

 " alatus, Say, Ohio River. 

 " Hopetonensis, Lea, Darien, Geo. 

 " nasutus, Say, Arkansas. 

 <( radialus, Lam., Petersburg, Vir. 



Double lateral tooth in both valves. 



Unio complanatus, Lea, 6 specimens, Mohawk, N. Y. 

 " " " Genessee, N. Y. 



" " Schuylkill, Pa. 



" corrugalus, Lam., Pondichery, India. 



I860.] 



