LOWER CALIFORNIAN MOLLUSCA. 2O9 



almost % inch longer than type. Both are worn, dead 

 shells, but show faint vertical riblets on two nuclear 

 whorls. 



B. ExcELSus Gould, 1853. Four, presented by Mr. 

 Belding, are fine fresh shells, but one is bleached. The 

 two upper whorls have fine riblets, as in B. insccndcns, 

 etc. Shells thicker than the other species, more shining, 

 and outer lip more expanded than usual. 



B. iNSCENDENs W. G.B. 1861. Four living and 13 

 fresh, with 73 bleached shells, found near San Jose del 

 Cabo by Eisen, do not show much of the variation form- 

 ing var. hryanti, but he states that he found all on the 

 ground, so that ascending trees is doubtless only done in 

 the wet season, or not at all by some shells, thus account- 

 ing for the remarkable variations in form. Eleven from 

 the Sierra Laguna above the " fig region," 3,000 feet, are 

 larger, and have riblets on three apical whorls (not two 

 as in others), the largest also with one more whorl (8). 

 Nine of these have the divergent mouth. Six, dead, from 

 San Leonicio, 3,000 feet altitude, have fine revolving 

 striae cutting the lines of growth, as in B . froteus^ but 

 less deeply; the mouth also nearly straight. On three 

 presented by L. Belding, from between the cape and La 

 Paz, this roughness is stronger, being as much so as in 

 B . frotcns. It is noticed as a light striation in Binney's 

 description, but is now known to be quite variable in 

 several other species. Mr. Eisen also got 83 other spec- 

 imens from same mountains, above 3,000 to 4,000 feet 

 altitude, which are usually more robust in form and 

 shorter than the others, but many intermediate. I pro- 

 pose to call this extreme 



Var. BETvDiNGi, as he sent the first specimen of this 

 form in good condition from near San Jose del Cabo, 

 Mr. Bryant also finding one at Punta Arena (near latitude 



