Mr. E. A. Smith on the Genus Pytliina. 229 



d'Orbigny and R^cluz, and not from actual examination of 

 the species. 



The ligament is mainly internal, oblique (as in KeJUa.)^ 

 and posteriorly inclined and adjacent to the hinder tooth ; a 

 narrow linear extension of it borders the hinge-margins 

 between the umbones. The lower internal margins of the 

 valves are minutely denticulate, the denticles being rather 

 stronger at the ends than in the middle. Tlie entire external 

 surface is minutely punctate, like some of the species of 

 Lepton ; but this feature is only visible under a powerful 

 lens. 



2. ^^Fythina .DesJiayesii^ d'Orb. & Reel.," H. & A. Adams. 

 (PI. XIII. A. fig. G.) 



1844. Erycina Deshayesii, Recluz, Rev. Zool. 1844, p. 325. 



1850. Myllita Deshayesii, d'Orbigny aud liecluz, Joiu'ii. de Conch. 1850, 



p. 292, 1)1. xi. figs. 12-14. 

 1858. Pythina Deshayesii, d'Orb. & Reel., H. & A. Adams, Gen. Rec. 



Moll. vol. ii. p. 476. 

 1862. Fythina IJeshaysii, Ohenu, Man. Concli. vol. ii. p. 126, fig, 602. 

 1865. Pythina Deshayesi, d'Orb., Angas, Proc. Zool. Soc. 1865, p. 652. 

 1878. Mylitta Deshayesii, Kobelt, Illiist. Couchylienbuch, pi. ciii. 



fig. 11. 

 1875. Pythina tasmanica, Tenison- Woods, Pi'oc. Roy. Soc. Tasman. 



1875, p. 162. 

 1887. Pythina tasmanica, Tate, Trans. Roy. Soc. S. Austral, vol. ix. 



p. 98, pi. v. fig. 12. 



Hah. New Holland {Recluz), Adelaide {Brit. Mus.), Rapid 

 Bay, St. Vincent's Gulf, S. Australia [Angas), King's Island, 

 N.VV. of Tasmania {Tenison- Woods). 



The fact of this remarkable sliell having divaricate folds 

 doubtless induced Messrs. Adams, Chenu, Tenison- Woods, 

 and Tate to consider it congeneric with Fythina. It is quite 

 evident that none of them had an opportunity of comparing 

 the two hinges, or they would at once have perceived the 

 difference. Still it is surprising that Messrs. H. and A. 

 Adams should have made this mistake, for had they compared 

 the description of Mylitta * given by d'Orbigny and Rdcluz 

 with the specimens of Pythina Deshayesia?ia which they 

 figured themselves, or even with Hinds's description of the 

 hinge, they certainly would have held these genera distinct. 



1 feel convinced that d'Orbigny and Recluz have fallen 

 into an error respecting the pallial impression. After a most 

 careful examination of several valves of this and allied species 

 1 cannot discover a trace of the triangular sinus described 

 by them. 



* Inaccurately .spelt Myllita, J. de Conch. 1850, p. 288. 



