128 ISCHNOCHITON. 



I. RINUDENTATUS Carpenter, n. sp. Unfigured. 



Shell oval, much elevated, reddish ; jugum acute; mucro median, 

 scarcely elevated ; entire surface minutely granulose. Central 

 areas having about 12 subparallel bars, which pectinate the front 

 margin, their interstices decussated ; lateral areas having 3-4 gran- 

 ose radiating line, the anterior valve with 26, posterior valve 24 

 such lira?. Interior: anterior valve with 10, central 1, posterior 

 valve 9 slits; teeth acute; eaves conspicuous, subspongy, crenulated 

 by the sculpture ; sinus wide, short, laminate with about 6 teeth. 

 Girdle having moderate sized, wide, conspicuously striated, rather 

 regularly imbricating scales. Length 15, width 7 1 mill. ; diver- 

 gence 100. (Q>r.) 



Monterey, California. 



This shell has the color of I. mertensii, nearly the sculpture of 

 /. peetinulatus and the normal scales of this group. Like /. regu- 

 larix, it has the denticulate sinus of Chiton. (Q>r.) 



I. CLATHRATUS Reeve. PI. 26, figs. 31-34. 



Shell oval or oblong, elevated, the back carinated ; side slopes 

 straight ; lateral areas and end valves radially granulate-lirate, cen- 

 tral areas latticed. Color dingy yellow, clouded with black, or rarely 

 unicolored yellow or olivaceous. 



The lateral areas are raised and sculptured with about 5 radia- 

 ating, closely and conspicuously granose riblets, the posterior rib 

 wide or bifid ; strongly pectinated along the sutural edge. Central 

 areas having longitudinal narrow bars parallel to the dorsal ridge, 

 decussated by bars of almost equal prominence vertical to them, 

 producing the effect of a grating. Mucro depressed. 



Interior whitish, with olive or leaden rays under the umbones. 

 Sinus flat, denticulate; anterior valve having 11-12, central valves 

 1, posterior valve 14-16 slits; teeth rather sharp, but not thin 

 eaves solid; 



Girdle compactly covered with very convex scales, which are 

 quite obsoletely striated. 



Length 27, breadth 17 mill. 



Length 34, breadth 18 mill. 



Monterey and San Diego, California,' to La Paz, L. California* 



