NEW FOSSIL MOLLUSCA OF CALIFORNIA. 335 



are found necessary, which I will insert here. The first 

 described was P. subelongata Meek, from Vancouver 

 Island cretaceous, in the Transactions of the Albany In- 

 stitute, vol. iv, p. 42, 1857, and repeated, with a figure, in 

 Bulletin of Hayden's Geog. & Geol. Survey of the Ter- 

 ritories, vol. ii, 1896, p. 362, pi. 2. Meek gives the num- 

 ber of ribs as 16 to 25, a wider range of variation than I 

 find admitted in any other species, but whether caused by 

 variation or imperfection of specimens is uncertain. At 

 any rate, the figure shows that it is identical with that 

 described by Gabb as P. bretveri in the Pal. of Cal., i, 

 p. 152, pi. 22, fig. 123. Gabb was misled by too hasty 

 reference to Meek's first description, for he states that 

 "the marked difference in the number of ribs will at 

 once distinguish them, P. subelongqta having but 16 

 ribs." Gabb's second species, P. nasuta, may account 

 for Meek's 16-ribbed form, as Gabb gives its range from 

 12 to 16. 



Whiteaves considers both as identical with Orbigny's 

 P. royana of France, and states that Orbigny figures the 

 extremes of variation in ribs as from 10^ to 29, which 

 may arise from imperfection in the specimens. 



Five specimens from Pt. Loma, San Diego, called P. 

 brezueri by me in Bull, iv, State Mining Bureau, 1894, are 

 like it in form, but one has the high beaks of nasuta, and 

 all have fewer ribs than typical subelongata, but have lost 

 all shell, and being internal casts, cannot form certain 

 proof as to the number of ribs once on the outside. The 

 same is probably true of Gabb's P. oregonerlsis. The 

 nearest resemblance to P. progressiva is in P. occidentalis 

 Morton, from the Cretaceous of N. J. southward, which 

 has 25 to 30 ribs, but none of them triplicately divaricate. 

 But one Eocene species is recorded in the East, P. mary- 

 landica Con., of which no figure is accessible here. 



