438 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Genus Lepidochitona Gray, 1821 



6. Lepidochitona dentiens (Gould, 1846) 



(Plate I, figs. 7-9.) 



1846. Chiton dentiens Gould, Proc. Bost. Soc. Nat. Hist., v. 2, 



p. 145. 

 1852. Chiton (Onithochiton) dentiens Gould, Moll. U. S. Expl. 



Exped., p. 321, pi. 28, f. 433-433b. 

 1857. Chiton (?) dentiens Carpenter, Rep. Brit. Assoc. Adv. 



Sci., 1856, pp. 209, 318, 348. 

 1862. Chiton dentiens Gould, Otia Conch., p. 6. 



1864. Traehydermon psendodentiens Carpenter, Rep. Brit. 



Assoc. Adv. Sci., 1863, pp. 530, 606, 612, 649. 



1865. Ischnochiton (Traehydermon) psendodentiens Carpen- 



ter, Proc. Acad. Nat. Sci., Phila., 1865, p. 60. 

 1879. Traehydermon dentiens Dall, Proc. U. S. Nat. Mus., v. 

 1, p. 323. 



1892. Ischnochiton (Traehydermon) dentiens Pilsbrv, Man. 



Conch. (1), v. 14, p. 73, pi. 8, f. 61-65. 



1893. Traehydermon dentiens Pilsbry, Man. Conch., (1), v. 



15, p. 65, pi. 15. f. 26 (girdle scales). 

 not 1917. Traehydermon dentiens Chace, Lorquinia, v. 2, p. 

 30 (=Mopalia acuta). 



Diagnosis: Valves small, delicate, low, median ones more 

 or less obscurely beaked ; sculpture consisting of numerous low, 

 flat, round, even granules over the entire surface, showing more 

 or less tendency to form into longitudinal lines on the central 

 areas ; lateral areas fairly well defined in good material ; sutural 

 laminae wide and low, separated by a moderately wide but shal- 

 low sinus; tegmental border of median valves gently arcuate 

 in front ; teeth thin, sharp, barely projecting, in tail valve very 

 numerous and often bifid ; eaves spongy ; mucro a little anterior 

 of the middle, rather elevated, its posterior slope concave: 

 slits 11, 1-1, 10 to 15. 



Recorded Range: 



Pleistocene: Lower San Pedro Series — Nob Hill Cut, 

 San Pedro, California (!). 



Living: Esquimalt, British Columbia (Carpenter), to 

 Socorro Island, Revillagigedo Group, Mexico (Pilsbry): be- 

 tween tides. 



