Vol. XI] 



BERRY— FOSSIL CHITONS 



477 



Pleistocene: Formation doubtful — Deadman Island, San 

 Pedro, California ( !). 



Living: Monterey and Pacific Grove, California ( !). 



Material Examined: 



Remarks: Several valves in the Arnold and Oldroyd collec- 

 tions appear to represent a small species of Lepidozona which 

 evidently belongs to the puzzling sinudentatus-group, several 

 members of which have been described or named from the 

 vicinity of Monterey. Perhaps the chief reason this group 

 is more troublesome than most is that it is very insufficiently 

 known. Neither sinndentatus itself, not the apparently allied 

 decipiens Carpenter and berryi Dall have been any too ade- 

 quately described, and no figures appear to be extant of any 

 of these species. The fossil specimens show traces of a toothed 

 plate across the sinus as described for sinndentatus, while they 

 further agree very fairly with certain recent specimens from Pa- 

 cific grove which I tentatively refer to Carpenter's species. The 

 figures here given should serve to fix the identity of the pres- 

 ent form, in case sinndentatus proves to be a different thing. 



From other North American members of the Lepidozona- 

 group, whether recent or fossil, this species is easily separable 

 by reason of its small size, elevated outline, sharp dorsal ridge, 

 distinctly convex slopes (though the height and convexity 

 \ary more or less in accordance with the serial position of the 

 valves), numerous low, weakly granose, radial ribs of the 

 terminal areas, 3 to 6 similarly granose ribs on the lateral 

 areas, and the 12 to 15 strongly interlatticed, longitudinal ribs 

 on each side of the central area, these last being considerably 

 finer and closer in the jugal region. 



