40 



897 = Modiola pertenuis, Meek & Hatde^-, Prcc. Acad. Nat. Sci. March 

 l?:s, 51. 



89S = Modiola (Pema) formosa, Meek & Hatdex, ib. Dec. 1861, 439. 

 The names of these two shells should be written Pema pertenuis, 

 and P. formoaa, if Scopoli's name Volsdla is not adopted. 



907 = Venus unionides, Roemek, Ool. I, 109, tab. 8, fig. 6. This and 

 the two preceding species (904 and 905) belong to the genus 

 P/euro»ij/a, which name must be adopted if Myacites, Schlot., as 

 affirmed hj Bronn and Goldf., is not to be retained. 



910 — This, and 911, 912, and 913, are oulj placed provisionally in the 

 Jurassic list. 



912 — Should be written Neritina nebrascensis, if Humphrey's name Xeri- 

 t,-r,j is not to be adopted. 



914 = LIOPLACODES, JIeek. Type Melania (Potadoma) vetema, 

 ilEEK & Hatde>-, Proc. Acad. >"at. Sci. Phila. Dec. 1S61.444. 



Differs from the type of Lioplax, Troschel, in its more elon- 

 gated form, smaller body whorl, more constricted suture, and 

 particularly in haring the posterior extremity of the aperture 

 angular instead of rounded, owing to the oblique flattening of 

 the upper side of the body whorl. 



From the types usually included in Melania, it differs in 

 having the columella perforated by a small umbilical opening, 

 and the peritreme continuous. 



J i 



