64 PROVISIONAL AID TO THE STUDY OF TASMANIAN MOLLUSCA. 



valve 



two 



Very long, sub-cylindrical, straight ends 



gaping 

 Equivalve thick, gaping 

 Shell rounded, beats turned forward ; 



hinge teeth 2 — 2 

 Compressed, thin ligament, anterior 

 Shell rugosely striated and ribbed, 



sinus profound 

 Three diverging teeth in each 



ft Ligament internal. 

 Small, thick, produced behind 

 Thin, cartilage with a free ossicle 

 Ligament in a triangular pit ; 



cardinal teeth 

 Ligament in a triangular pit ; one 



cardinal tooth 

 Hinge with many teeth in a line, inside 



pearly 

 ** Pallial line simple. 

 f Ligament external. 

 Trigonal, radiately ribbed, inside pearly 

 Kadiately ribbed, cordate not pearly 

 Thin, orbicular, white, divaricating strias 

 Inequivalve thick, attached by left umbo 

 Sub-orbicular, smooth, ligament double 

 submarginal. No lateral teeth 

 Minute, thin, sub-oval, usually trans- 

 parent 

 ft Ligament internal. 

 Large, solid, oblong, ventricose, at- 

 tenuate behind, smooth or con- 

 centrically furrowed Crassatellidas.lxxxviii. 

 Eoundly ovate, strongly radiately ribbed Astartidse, Ixxxix. 

 Hinge, many teeth in a line, not pearly Areida, xciii. 

 Hinge, many teeth in a line, pearly 



inside Nuculidaj, xcii. 



(&.) Two adductor impressions, very unequal,umbones anterior. 

 Shell equivalve, oval or elongated, inside 



pearly 

 Shell large, equivalve wedge shaped, 



thin, brittle 

 Shell small, eared, thin, transparent, or 

 having pearly interior, often 

 gaping 



(c.) One adductor impression 

 Shell irregular, radiately ribbed, spiny, 

 usually 2 hinge teeth in each 

 valve Spondylidae, xcvii 



Solenidse, lxxii. 

 Saxicavidse, lxxiii. 



Semelidas, Ixxviii. 

 Tellinidse, lxxix. 



Petricolidse, lxxxii. 

 Veneridffi, lxxx. 



Corbulidffi, lxxiv. 

 Anatinidse, lxxv. 



Mactridse, lxxvi. 



Paphiidae, Ixxvii. 



Nuculidffi, xcii. 



Trigoniidse, xci. 

 Cardidas, Ixxxiii. 

 Lucinidffl, lxxxv. 

 Chamidee, Ixxxiv. 



TJngulinidse, lxxxvi. 



Erycinidse, lxxxvii. 



Mytilidae, xciv. 

 Pinnidffi, xcvi. 



Aviculidffi, xcv. 



