352 



Nuculana obolella, Tate (sp.). 



1886. Zeda obolella, Tate, Trans. Eoy. Soc. South Aust. vol. viii. p. 129, 



pi. T. figs. Zor-b. 

 1893. Leda obolella, Tate and Dennant, id. vol. xvii. pt. 1, p. 224. 

 1895. Leda obolella, Tate and Dennant, id. vol. xix. pt. 1, p. 113. 



This shell can be distinguished with facility, being oval and 

 fragile ; the hinge is narrow, much contracted, and the teeth are 

 very small ; in addition, it is not rostrated, and the surface is only 

 very faintly striated concentrically. It is by no means a typical 

 example of the genus. 



Dime7isions. — Height 9 mm. ; length 12-5 mm. 



Form, and Loc. — Eocene : Muddy Creek, Victoria. 



L. 9825. Examples of the neanic and ephebic stages of growth. 



Purchased. 



Family TRIGONIID^. 



Genus TRIGONIA, Bruguiere. * 



[Ency. Meth. Vers. t. i. 1789, p. xiv. ; Lamarck, Syst. Anim. sans Vert. 1801, 

 p. 116.] 



Shell thick, subtrigonal, oval, or subtrapezoidal, inequilateral ; 

 umbones directed posteriorly ; cardinal teeth divergent, transversely 

 striated ; impression of the anterior adductor of the valves smaller 

 than that of the posterior, deeper, and placed on the cardinal ' 

 border ; ligament marginal, thick ; surface of the valves commonly 

 ornamented by radiating ribs, or tubercles ; interior of the shell 

 nacreous. 



Type. — Trigonia nodulosa, Lamarck. 



Trigonia subundulata (M'Coy MS.), Jenkins. 



1865. Triffonia subundulata (M'Coy MS.), H. M. Jenkins, Quart. Journ. 



Sci. vol. ii. p. 362, pi. viii. fig. 6. 



1866. Trigonia semiwidulata, H. M. Jenkins, Geol. Mag. vol. iii. p. 201. 

 1866. Trigonia semiimdulata, M'Coy, id. vol. iii. p. 481. 



1876. Trigonia semiundulata, M'Coy, Prod. Pal. Vict. dee. ii. p. 22, pi. xix. 



figs. 4-5. 

 1878. Trigonia semiundulata, E.. Etheridge, jun., Cat. Aust. Foss. p. 158. 

 1886. Trigonia semiundulata, Tate, Trans. Roy. Soc. South Aust. vol. viii. 



p. 145. 



