234 Mr, E. A. Smith on the Genus Pytliiiia. 



18. " PytMna compacta^ Gould " (Tiyon). 



Kellia compacta, Gould, Proc. Boston Soc. Nat, Hist. 1861, vol. viii. 



p. 33 ; Otia Conch, p. 173. 

 Pythina compacta, Tryon, Proc. Acad. Nat. Sci. Philad. 1872, p. 232. 



Hah. ? 



Respecting the hinge of this species Gould writes : — " Val- 

 vule altera dentibus duobus magnis, divergentibus, equali- 

 bus ; alterffi irarginibus dentibus simulantibus, elongatis ; 

 fossa ligamentali arapla." " Its hinge is like that of Pythina^ 

 Hinds. A knowledge of the animal can alone remove it 

 definitely from the old genus Kellia^ 



From this two things are evident : firstly, that this species 

 belongs to Tellimya^ and, secondly, that Gould did not know 

 Pythina nor the exact dentition of Kellia. 



Trjon was probably induced to place this species in 

 Pythina through Gould's statement respecting its similarity 

 of dentition. 



19. Pythina rugifera^ Carpenter. 

 Pythina rugifera, Carpenter, Proc. Acad. Nat. Sci, Philad. 1865, p. 57. 



Hah. Puget Sound, west coast of North America. 



The hinge of this species is thus described by Carpenter : — 

 " Dente cardinali uno minore, clavicula antica laterali incon- 

 spicua ; laterali postico nullo." This description shows that 

 the shell in question is quite distinct from Pythina { = Kellia). 

 Without seeing a specimen it is impossible to state its true 

 position ; but temporarily I suggest its location in Montacata, 

 from the fact of there being no posterior teeth. 



Conclusions. 

 From a perusal of the preceding observations it will be 



seen- 



(1) That the so-called genus Pythina difFers from Kellia 



only in having the surface ornamented with divari- 

 cating plica3, a feature, in my judgment, only of 

 specific value. 



(2) That it is restricted to one species, namely P. 

 Deshayesiana of Hinds. 



(3) That the eighteen other species which have been located 

 in Pythina should, according to their conchological 

 characters, be thus classified : — 



