364 CALIFORNIA ACADEMY OF SCIENCES. 



tures of the study of the paleontology of the Tertiary and 

 post-Tertiary of California is in studying the changes 

 which have taken place in species which did not migrate, 

 or in tracing the relation between living and old or ex- 

 tinct species of the same type. Lack of time and lack 

 of. material have prevented studying this subject as the 

 writer had hoped to do. The few notes given are those 

 taken down in determining the fossils. These notes will 

 be given under the descriptive paleontology, but a few 

 instances of such changes are noted at this point. 



Thus, Cardiimi corbis Marty n and Cardium meekianuni 

 Gabb, appear to grade into each other in such a way as 

 to suggest that C. corbis is simply the living representa- 

 tive of C . meekianuni, no break coming between them. 

 In the Pliocene at San Pedro is a Chlorostoma which 

 agrees perfectly with C . funebrale A. Adams, except that 

 the last coil is sculptured with a number of strong revolv- 

 ing ribs, the recent species usually having only two, the 

 anterior one rather faint, and a few obsolete ribs. A large 

 number of recent and fossil forms were examined with- 

 out showing any intermediate specimens. 



A comparative study of Crepidula grandis Midden- 

 dorf with C. rugosa Nuttall and C. excavata Broderip 

 may show a very close connection. The Miocene forms 

 of Lunatia lezvisii Gould are found to differ from the liv- 

 ing in uniformly lacking the constriction near the suture, 

 which is so marked in large living specimens and upon 

 which Gould lays great stress in his description of the 

 species. The Pliocene specimens of Monoceras engona- 

 tum Conrad differ from those living along the coast to-day 

 in being from one and one-half to double the size. The 

 same thing is true of some of the Purpuras. 



