376 * MEXICAN BOUNDARY SHELLS— BALL. 



besides a much larger shell. In E. arnhehni the nucleus is punctate, as 

 in ramentosfi, and followed by (rlose-set stri;i; in harmony with tlie lines 

 ofurowth, the intervals between which are like elevated threads, the 

 surface of which is broken into low pustules which become more close- 

 set and elongate as the shell grows; the earlier ones are rounded ami 

 rather sparse, the later ones are irregularly disposed along- the threads, 

 the intervals between them having no regularity and not forming 

 oblique channels or a pattern but tending to arrange themselves, so far 

 as they are arranged at all, in horizontallj' revolving lines. 



I have no doubt that this shell is distinct from either ranienfo.sa or 

 exarata and have named it for Mr. J. S. Arnheim, of San Francisco, 

 California, by whom the majority of specimens seen were collected. 



EPIPHRAGMOPHORA KELLETTII, Forbes. 



Monument No. 258, on the boundary line, also at Campo and Ocean 

 Beach, San Diego County, and the San Ysidro ranch, Lower California. 



EPIPHRAGMOPHORA INTERCISA, Binney. 



San Clemente Island. 



EPIPHRAGMOPHORA STEARNSIANA, Gabb. 

 San Clemente Island ; Colorado Islands. 



EPIPHRAGMOPHORA GABBI, Newcomb. 



San Clemente Island. 



GLYPTOSTOMA NEWBERRYANUM, Binney. 



Nachoguero Valley, and Campo, San Diego County. 



MELAMPUS OLIVACEUS, Carpenter. 

 La Jolla, near San Diego. 



PHYSA HUMEROSA, Gould. 



Subfossil near monument No. 219. 



AMNICOLA PROTEA, Gould. 



Subfossil with the last. 



MARINE MOLLUSKS. 



As the termination of the boundary line is at the Pacific Ocean, Dr. 

 Mearus was able to collect a number of marine species on the shore, 

 and others during a visit to San Clemente Island, which lies west from 

 the shore of San Diego County, about 00 miles in the Pacific, forming 

 the southernmost of the Santa Barbara group of islands. Those to 

 which no lotjalitj' is appended were obtained at the end of the boundary 

 line just south of San Diego. 



