— 14 — 



— supra recta usque ad angulum, dein recte descen- 

 dente ; antice rotundata , inferne decurrente ; infra 

 convexa ; postice (regio postica sesquiduplicem ante- 

 rioris sequans et inferne ad 20 millim. post vertica- 

 lem leviter crescens) in rostrum late rotundatum 

 subinferumque attenuata; — umbonibus inflato-ro- 

 tundatis, prominentibus (nates acuti, rugulosi) ; sulco 

 dorsali indistincte ; area subcompressiuscula ; cardine 

 relative robuste ; dente cardinali bipartite : unus 

 elongatus prope marginem ; alter sat crassus, medio- 

 criter productus, truncatus ac denticulatus ; lamella 

 laterali relative perelongata, recta, sat compressa, 

 mediocriter producta, cultrata; ligamento posteriori 

 brevi, castaneo, prominulo ; lunella perelongata, inter 

 lamellam et marginem. 



UNIO LAVIGERIANUS 



Long. max. 59 ; ait. max. et vert, œque 38 ; crass. 

 max. 30 ; basis apico-rostralis 47 ; intervallum e nati- 

 bus ad angulum 30, ex angulo ad rostrum 22, e rostro 

 ad verlicalem 35 et e basi verticalis ad angulum 41; 

 regio antica 20, postica 39 millim. 



Concha subangulato-ovata, obscure in ventre val- 

 varum subsinuosa, postice in altitudine sat ampla, 

 relative crassa ac ponderosa, parum nitente, concen- 

 trice bene striata (striae ad peripheriam rudiores ac 

 subfoliacese et in regione antica sulculis radiantibus, 

 sat prominulis, eleganter interruptse) ac superne ru- 

 goso-striata ; atra, ad umbones rubra (in specimine 

 non adulto luteo-nigrescente); intus pallide carneo- 



