120 CLASS I. TROPIOPODA. ORDER I. BIMUSCULOSA. 



Examples. 

 PI. XC. Fig. 1. 

 Hyria Syrmatophora, Sowerby, Genera of Shells, No. 16. Lister, 



Conch., pi. 160. f. 16. 

 My'a Syrmatophora, Linnaeus. 

 Viiio Syrmatophorus, Lea. 

 Unio avicularis, Deshayes. 

 Hyria avicularis, Lamarck. 

 Prisodon obliquus, Schumacher. 

 THptodon rugosus, Spix. 



PI. XC. Fig. 2. 



Hyria corrugata, Lamarck, Anim. sans vert., new edit., vol. vi. p. 562. 



Enc. Moth., pi. 247. f. 2, a, b. 

 Mya angulata, Wood. 

 Unio corrugatus, De Blainville. 

 Unio angulatus. Lea. 

 Pnxyodon ponderosus, Schumacher. 

 Diptodon (corrugatus?), Spix. 



ANODON, Bruguiere. 



Testa transversa, sequivalvis, inequilateral is, plerumque tenuis, epider- 

 mide viridi induta, interne submargaritacea. Cardo linearis, eden- 

 tulus, ligamento elongato, externo. Impressio muscularis postica, 

 semper composita. 



This genus was instituted by Bruguiere for the association of certain 

 species selected from the Linnaean Mya, under the title of " Les Ano- 

 dontites?' The simple term Anodon, signifying without teeth, has been 

 adopted as most expressive of the character by which they are distin- 

 guished from the rest of the Naiades. In accordance, however, with our 

 observations at the commencement of this family, it will be found, that in 



