THE FAMILY OF UNIONIDJE. 



X\ II 



Lamproscapha. Swain., 

 Sympkynota. Lea, 

 Anodonta. Lam., 

 /A niiodon. Swain , 

 Patularia. Swain., 

 Calceola. Swain., 

 A lasmodonta. Say, 

 Uniopsis. Swain., 

 Afaryaritana. Sdmm., 

 Cornplanaria. Swain., 



ivinvsmtrd by Anodonta tiliquota. Spix. 

 " " Unio Ivevissimus. !> 



" " An. cyjnea. Lam. 



An. areolatus. (edentula. Say.) 



An. rotundus. Spix. 



Unio cakeolus. Lea. 



Alas, undulata. Say. 



U. mytiloides. Raf'.? 



M. margaritifera. Lin. 

 ruyosa. Barnes. 



Swain. 



Retzius, Nova Testiceorum Genera? 178S, established the genus t/m'o, of which 

 he makes two divisions, viz.: 



* Without lamellar teeth 



1. Unio maryaritiferus. Represented by Mya margaritifera. Lin. 



** With lamellar teeth 



2. Unio crassus. 



3. Unio tumidus. 



4. Unio pictorum. 



5. Unio ovalis. 



6. Unio corruyatus. 



Unio crassissirnus. F> r. 



Unio ovalis, of British Zoologists. 



Unio pictorum. Lin. 



Unio tumidus. Retz. 



Unio corruyatus. Lam. 



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

 Lamarck's Nayades into three Families, viz.: 



Family 9th. UNIONID.E. 10th. MUTELAD.E. llth. MYCETOPODID.E. 



The Unionidw consists of nine genera, viz.: Anodonta, Guv.; Maryaritana, Schum.; Afonocon- 

 dylcea, D'Orb.; Unio, Retzius; Barlala, Humph.; 'Lamproscapha, Swain.; Anodonta, Lain.; 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 llth. MYCETOPODID^ consists of one genus, viz.: JLTyceti^ma, D'Orb. 



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



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

 Academy of Natural Sciences. The establishment of the genus Unio has lnvu usually uivrn. l>\ I-'ivm-li 

 authors, to Bragaiere, but the English and German writers oivo it to Ret/ins so universally, that I have 

 followed them. The author of this dissertation would appear from the title-page to lie L. M. 1'liilipsson; 

 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. v 



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

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

 ally and specifically, viz., the Iridina ovata, Swain. 



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