THE FAMILY OF UNIONID^. 



Lamproscapha. Swain., 

 Symphynota. Lea, 

 Anodonta. Lam., 

 Hemiodon. Swain , 

 Pattdaria. Swain., 

 Calceola. Swain., 

 A lasmodonta. Say, 

 Uniopsis. Swain., 

 Margaritana. Sclium., 

 Gomplanaria. Swain., 



represented by Anodonta siliquosa. Spix. 



" " Unio Isevissimus. Lea. 



" " An. cygnea. Lam. 



" " An. areolatus. {edentida. Say.) Swain. 



" " An. rohmdus. Spix. 



" " Unio calceolus. Lea. 



" " Alas, undulata. Say. 



" " U. mytiloides. Eaf.? 



" " M. margaritifera. Lin. 



" " Alas, rugosa. Barnes. 



Eetzius, JSfova Testaceorum Oenera,^ 178S, established the genus Unio, of which 



he makes two divisions, viz. : — 



* Witliout lamellar teeth — 



1. Unio margaritiferus. Eepresented by Mya margaritifera. Lin. 



Witli lamellar teeth — 



2. Unio crassus. 



3. Unio tumidus. 



4. Unio pictorum. 



5. Unio ovalis. 



6. Unio corrugatus. 



Unio crassissimus. Fer. 



Unio ovalis, of British Zoologists. 



Unio pictorum. Lin. 



Unio tumidus. Eetz. 



Unio corrugatus. Lam. 



Mr. Gray, in his excellent List of Genera (Zool. Soc. Proceedings, 1847), divides 

 Lamarck's JSfayades into three Families, viz. : — 



Family 9th. Unionid^. 10th. Mutelab^. 11th. Mtcetopodid^. 



The Unionidee consists of nine genera, viz.: Anodonta, Guv.; Margaritana, Schum.; Monocon- 

 dylcea, D'Orb.; Unio, Eetzius; Barhala, Humph.; Lamproscapha, Swain.; Anodonta, Lam.; Byssano- 

 donta, D'Orb; Glabaris. 



Family 10th. Mutelad^e consists of five genera, viz.: Mutela, Scopoli; Leila, Gray; Pleiodon,^ 

 Con.; Paxyodon, Schum.; Prisodon, Schum. 



Family 11th. Mycetopodidj!: consists of one genus, viz.: Mycetopus, D'Orb. 



M. D'Orhigny, in his Voyage Am. Merid., vol. v. p. 594 (1835 to 1843), divides 



^ I have never been able to examine this rare work until recently, it being now in the Librar^^ of the 

 Academy of Natural Sciences. The establishment of the genus Unio has been usually given, by French 

 authors, to Bruguiere, but the English and German writers give it to Eetzius so universally, that I have 

 followed them. The author of this dissertation would appear from the title-page to be L. M. Piiilipsson; 

 Retzius being the presiding officer of the institution. But it is understood to be a fact that papers writ- 

 ten by officers of the Universities in Germany have been sometimes published under the names of students 

 as Theses, and it is said that this is one of such cases. 



2 I do not see any reason for throwing out Iridina and taking in its place the name of Pleiodon, 

 which was unnecessarily given to a shell well known and figured long before, and described both generic- 

 ally and speciflcallj", viz., the Iridina ovata, Swain. 

 E 



