CALIFORNIA ACADEMY OF SCIENCES. 249' 



mile south of Weber creek (Cold Springs), under an old log, 

 between Coloma and Placerville, in 1849-50." This is Mr. 

 Moores' own account, but the specimen being inseparable 

 from Ophiogyra helig mo idea of tropical America, it is generally 

 considered an error caused by the misplacement of labels. 

 There is a bare possibility that such stragglers or their eggs 

 may have been introduced by birds or travelers accidentally, 

 and lived a short time here, but they cannot be considered 

 as native species.* 



In support of Mr. Moores' case, however, there is another 

 specimen much like his, but bleached and without teeth, 

 sent to Mr. H. P. Carlton as "found under a log in Cala- 

 veras Co." I may add that I have collected within ten miles 

 both north and south of these localities, without finding 

 any specimens resembling the above. 



The fourth species (or specimens) of discoid sub-fossils 

 have been in my hands since 1871, when Mr. C. D. Voy 

 brought them to me as discovered by him "in an Indian 

 mound north of S. F. Bay." They are of the size and nearly 

 the form of Helicodiscus lineatus (a species said to occur in 

 California), but without a trace of teeth or sculpture. I 

 considered them, however, imperfect specimens of that form 

 until 1883, when W. O. Emerson found a few of the same 

 much larger but more fossilized, near Haywards, on a slid- 

 ing bank, where they seemed to have come from under the 

 roots of a large tree that had been undermined. These also 

 are toothless, and some of both sent to Mr. Bland and Mr. 

 Binney, have been decided to be of a new species if not new 

 genus. As with the specimens of Hyalina, mentioned be- 

 fore, these were where they could not have been washed 

 down by the mountain streams. 



Without living specimens it will be inadvisable to describe 

 these, especially as their being found first in an Indian 

 mound is some indication that they may increase instead of 



~See Amer. Jour. Couch., V, 196 to 219; 1870. 



