CO^CHYLIA—DITHYRA. xxvii. 



9. fragilis, Jlexurd longitudinali anticd. 



witli a longitudinal flexure ai the anterior side, 



10. radiata, striis minutis longitudinalibus reticulata. 



reticulate by minute longitudinal strise. 



24. GOODALLIA. 



1. triangularis, margine interno denticulato. < 



with the inner margin toothed. 



2. minutissima, margine interno integerrimo. 



with the inner margin very entire. 



25. SOLEN. 



* valvis unidentatis. 



with a single tooth in each valve, 



1. Vagina, dentihus complanatis. 



with the teeth flattened. 



2. Novacula, dentibus conico-acuminatis. 



with the teeth rather conic and pointed. 



** valvd alterd hidentatd. 



with two teeth in one Valve. 



3. Siliqua, rectus, dente solitario hastato-acuminato. 



straight, with the single tooth spear-shaped and 

 pointed. 



4. Ligula, rectus, dente solitario obtuso Jisso. 



straight, with the single tooth obtuse and cloven 

 •'5. En sis, subarcuatus, dentibus simplicibus. 



slightly curved, with (he two teeth simple. 

 * C.2 



